Having just spent the last month cleaning up a DB which was very 1st normal running an ASP front end and some interesting T-SQL I would stringly encourage you to go normalised and make it parent child.

With SQL 2005 it is so easy to do and if you are using SP to access / edit and modify your data anyway it is very easy to maintain.

What you are suggesting with storing all the Cust ID's in a string will become a PITA very quickly when you start working with it.