I have the Asrock P55 Pro with the i5-750. In retrospect, for the few extra bucks, I would have gone with the Gigabyte GA-P55-UD3R. It has a much better bios than any of the Asrock P55 MBs. There is also the unresolved issue of frying an Asrock P55 Pro if you raise the CPU voltage too high.
Review at TH..
For what you are going to use the computer for:
Gigabyte GA-P55-UD3R $140. from
Newegg
Intel i5-750 $200. from
Newegg, unless you live near a Microcenter $150. + tax
G.SKILL Ripjaws Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 Model F3-12800CL9D-4GBRL $86. from
Newegg, x2 if 8GB.
Cooler Master Hyper 212 Plus CPU HS $19.26 + shipping from
Provantage. Complaints about being difficult to install, but only took me about 15 minutes with no problems. Review at
Frosty Tech. Thread here on 1156 heat sinks that won't block ram slots
Link
Second 120mm fan for CPU HS $10 - $15. for a good fan + shipping
DVD burner?
Thermal Paste? You can use the stuff that comes with the heat sink or buy something better. $5 - $7 + shipping
I didn't add everything up, but it should be below your budget.
And get an extra 2% off Newegg purchases with
Bing Cashback.
Asrock P55 Pro, bios V1.90, i5-750 3.80 Ghz @1.325V bios, Cooler Master Hyper 212 Plus (2 fans) with TIM Consultants T-C Grease 0098, G.Skill Ripjaws 4GB (2 x 2GB) DDR3 1600 @ 760 Mhz 9-9-9-24, 1.5V, OCZ ModXStream Pro 700, MSI NX8800GT, Lian Li PC-7A Plus case (original 120mm ADDA front & rear fans), NEC 3540A, Win 7 Ultimate 64bit