I used a built in function to create comma separated string using List easily. (It is not split and join but new function) I'm not able to recollect or find it. If some one knows about it and uses it please post a link to that. Framework - .net 2.0
(It is not Join or split - I know about this, .net has new built in function to create CSV format)
Check Jacob G Answer below for what i was looking for let me know your thoughts on it compared to join ;)
And whoever gave me -ve rep need to keep some patience and not hurry