Hi Judy,
Do you play cash games or tourneys? How many players do you usually have? Generally a 500 chips set with 4 colors can get by most games. Also, I prefer denoms as it is easier than someone asking what each color is every ten minutes. You can use the 25 as either $25 or 25c.
Also, what is your budget? There are a lot of nice poker chips sets for a decent price. If you can afford too, I'd avoid the plastic slug dice chips, though.

There are ton's of sites, but here are a couple of links that you can check out to see what is available:

This is David Spragg's site:

http://poker.marlowcasinochips.com/

Jim Shaffer's Site

http://www.thechiproom.com/

Josh Shore's site:

http://www.apachepokerchips.com/

I prefer to use real casino chips when I play poker, though.