1: 4.5 GIGA Hashes, is 4500 MEGA Hashes, Giga being 1,000,000,000 and Mega being 1,000,000
2:Dont expect 500 Bitcoins a month with a Jalepeno.
The average time to generate a block at 4500.0 Mhps, given difficulty of 3651011.0, is 5 weeks, 5 days, 7 hours, 58 minutes, and 33 seconds
So by solo mining you should be able to get one block every 6 weeks or so netting you 25 BTC every 1½ month.