So far pretty good.... Looks like your going for Brawn over Brains though (Pairing a 6600GT with Semperon definite CPU hold backs)
If i could make a recommendation look at investing in the 64bit Semperon Processor's (Will Destroy a XP or 32Bit Semperon) it will require you to switch your mobo to a socket 939 (Will lead to future upgradeability, whenever you have spare $$$ invest in a Athlon 64 without having to purchase a new mobo) The Price difference between the Semperon64 and 32 is about $20... And look at a decent brand Mobo (ASUS or MSI)
With Semperon 64 : 8/10 for Budget system
Without Semperon 64: 6.5/10