Athlon
No matter what else you do, get an Athlon.
One other piece of advice I would give you is to get a motherboard with onboard video that can be turned off in BIOS. That way, you can save money now, but expand the video with a sweet card later....if you choose.
for future reference
ping
For the love of God, don't go with onboard video. It's slow, steals resources, and cripples performance. For basic browsing and email, even the ancient Genoa Phantom I used in my previous personal machine was an improvement over onboard. A cheap AGP Geforce that's a generation or 2 old but still very servicable for anything but high end games should only set you back around $50 or so.
Try newegg.com for everything...hubby got a very nice video card there recently at a good price, and I've used them in the past to buy cpu upgrades. They ship fast and are very reasonably priced.