Nice build................except for the Acer monitor.
I've built a number of "Budget" builds for clients & friends and looking at yours it's real nice.
I usually try to get something for nothing in my budget builds so overclocking is the name of the game. Too bad you couldn't get your hands on a unlockable & stable X2 550. Quad for free and overcloks as well.
As for ram since the Phenom Quad & your motherboard choice can use faster ram, not talking about DDR3, why not go for some G.Skill PC2-8500 at just $3 more?
Buy G.SKILL F2-8500CL5D-4GBPK PC2-8500 4GB 2X2GB DDR2-1066 CL5-5-5-15 240PIN Dual Channel Memory Kit
I also swear by this mouse which costs much less than the Logitech you list. It's the OCZ Behemoth.
OCZ Behemoth Laser Gaming Mouse W/ 2 Way Scrolling Wheel 800-3200DPI Adjustable Weights - DirectCanada
Still I like the look of your build, but ditch the Acer ASAP!.