Not many if you get super lucky you might find a block worth 50 in a day. You are mining @ about 10 mhash/s where even a cheap block erupter gets 300 mhashes/s.

To put it in numbers you can see plainly:

1000 hash/s = 1 Khash/s
1000 khash/s = 1 mhash/s
1000 mhash/s = 1 ghash/s

so you are mining @ 11,000,000 hash/s competing to find block with people who are mining @ 1,000,000,000+ hash/s