Seleccionar un solo check y enviarlo a la BD

[Diosus]

Código PHP:

 <form action="guardar2.php" method="post"  name="form1" id="form1" > 
            <table width="535"  border="0" align="center" cellpadding="3" cellspacing="0"> 
                <tr class="style5"> 
                  <td colspan="3"><div align="center"><br> 
                      </div></td> 
                  </tr> 
                <tr class="style5"> 
                  <td width="43%"><strong>Nombres</strong></td> 
                  <td colspan="2"><strong>Apellidos</strong></td> 
                </tr> 
                <tr class="style5"> 
                  <td> 
                    <div align="left"> 
                      <input name="nombres" type="text" size="37" maxlength="100"> 
                    </div></td> 
                  <td colspan="2"><input name="apellidos" type="text" size="37" maxlength="100"></td> 
                </tr> 
                <tr class="style5"> 
                  <td><div align="left"><strong>N&ordm; Documento de Identidad</strong></div></td> 
                  <td width="27%"><strong>Tel&eacute;fono Fijo </strong></td> 
                  <td width="30%"><strong>Tel&eacute;fono Celular </strong></td> 
                </tr> 
                <tr class="style5"> 
                  <td> 
                    <div align="left"> 
                      <input name="dni" type="text" size="30" maxlength="12"> 
                    </div></td> 
                  <td><input name="telefono_fijo" type="text" size="17" maxlength="20"></td> 
                  <td><input name="telefono_celular" type="text" size="17" maxlength="20"></td> 
                </tr> 
                <tr class="style5"> 
                  <td><strong>Lugar de trabajo </strong></td> 
                  <td colspan="2" valign="top">&nbsp;</td> 
                </tr> 
                <tr class="style5"> 
                  <td colspan="3"><input name="lugar_trabajo" type="text" size="78" maxlength="80"></td> 
                </tr> 
                <tr class="style5"> 
                  <td colspan="3"><strong>Cargo </strong></td> 
                  </tr> 
                <tr class="style5"> 
                  <td colspan="3"><input name="cargo" type="text" size="78" maxlength="80"></td> 
                  </tr> 
                <tr bgcolor="#ABC9DC" class="style5"> 
                  <td><div align="right"><strong>Evento en el que desea<br> 
                    Registrarse 
                  </strong></div></td> 
                  <td colspan="2" valign="top"> <p> 
                    <input name="abc" type="checkbox" id="abc" value="abc"> 
                    COSTOS ABC  (28,29,30 Agosto) <a href="http://www.bqm.com.pe/cabc_ago.html" class="style7">[ + ]</a> <br> 
                    <input name="iso" type="checkbox" value="iso">  
                    Implementaci&oacute;n  ISO 9001:2000 (1,2 Set) <a href="http://www.bqm.com.pe/iso_ago.html" class="style7">[ + ]</a> 
                    <br> 
                    <input name="gest" type="checkbox" value="gest"> 
                      GESTION ADMINISTRATIVA (4,6,8 y 9  Set) <a href="http://www.bqm.com.pe/ga_ago.html" class="style7">[ + ]</a><br> 
                    </td> 
                </tr> 
                <tr class="style5"> 
                  <td colspan="3"><strong>Indique en que otros cursos estar&iacute;a intersado</strong></td> 
                  </tr> 
                <tr class="style5"> 
                  <td><input name="seleccion" type="checkbox" id="seleccion" value="sigma"> 
a. Six Sigma <br> 
<input name="seleccion" type="checkbox" id="seleccion" value="costabc"> 
b. Costeo ABC <br> 
<input name="seleccion" type="checkbox" id="seleccion" value="admipers"> 
c. Administraci&oacute;n de Personal <br> 
<input name="seleccion" type="checkbox" id="seleccion" value="mktestra"> 
d. Marketing Estrat&eacute;gico <br> 
<input name="seleccion" type="checkbox" id="seleccion" value="impleiso"> 
e. Implementacion del ISO 9001:2000 </td> 
                  <td colspan="2" valign="top"><input name="seleccion" type="checkbox" id="seleccion" value="gestadm"> 
f. Gesti&oacute;n Administrativa<br> 
<input name="seleccion" type="checkbox" id="seleccion" value="gestestra"> 
g. Gesti&oacute;n Estrat&eacute;gica <br> 
<input name="seleccion" type="checkbox" id="seleccion" value="balanced"> 
h. Balanced Score Card <br> 
<input name="seleccion" type="checkbox" id="seleccion" value="planestra"> 
i. Planeamiento Estrat&eacute;gico </td> 
                </tr> 
                <tr class="style5"> 
                  <td><div align="right"><strong>N&ordm; de operaci&oacute;n de la<br> 
                        Boleta de Dep&oacute;sito (Voucher)</strong></div></td> 
                  <td colspan="2" valign="top"><input name="n_operacion" type="text" size="35" maxlength="12"></td> 
                </tr> 
                <tr class="style5"> 
                  <td><div align="right"><strong>Correo para enviarle su usuario y contrase&ntilde;a de acceso al  
                    Club de <br> 
                    Gesti&oacute;n Estrat&eacute;gica</strong></div></td> 
                  <td colspan="2" valign="top"><input name="email" type="text" size="35" maxlength="100"></td> 
                </tr> 
                <tr class="style5"> 
                  <td colspan="3"><div align="center">                       
                  <input name="submit" type="submit" value="Enviar" onClick="return verifica(this.form)"/> 
                      <br> 
                      <input name="fecha" type="text" class="mini_blanco" value="<? echo date ("j-F-Y"); ?>" size="15" maxlength="15" readonly="true"> 
                      <input name="hora" type="text" class="mini_blanco" value="<? echo date ("H:i "); ?>" size="10" maxlength="10" readonly="true"> 
                  </div></td> 
                  </tr> 
              </table> 
          </form>