Hi, I started mining a few months ago at around 1GHash 3x 333MHash usb dongles. Currently with BTC guild that is seeing about 0.01BTC every 7-10 days. the dongles cost me around 0.2BTC each couple months ago.
I think it'd be more profitable to start mining an altcoin such as Litecoin or Primecoin if you already have some decent graphics cards.

I haven't tried any other ones for Bitcoins but BTC Guild also mine Namecoin at the same time. There are a few others that mine others such as IXC and DEV coin as well.

Have a look at the site: https://en.bitcoin.it/wiki/Comparison_of_mining_pools
it's a good starting point to judge what pool would suit you, or at least where to start

Mining bitcoins is very much a secondary means now (for me). Most comes from link revenue, market trades and stock holdings.

Hope this helps