Help My iMac Is Locking Up A Lot

I understand that this is not my G5 or even the powerhouse DELL I have in my downstairs office. But listen this iMac has locked up a lot since I have been putting it to the test.

I would say this puppy has locked up at least 10 times since I have purchased it.

I am not compiling large amounts of C code, I am not crunching HD video. The test that I am putting it through is keeping multiple safari windows open with one or two java applets going. Doesn't sound like a lot, huh? Well this 1gig version looks to be inadequate for heavy web surfing. I will research and see if any one else has experienced this problem