That's a good combination (GA-EP45-UD3P, $115 after rebate) + E8500 ($188) but if you're going to upgrade the CPU anyway and you're getting a GA-EP45-UD3P, then your only reasonable upgrade choice is Q9550, $280. You might as well get the Q9550 now instead of upgrading later. Your total cost would be lower and you get the full speed right away.
Q9550 $280
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115041
If you're not a gamer and you don't need Crossfire/RAID/FireWire you could also get a simpler MB and save some cash.
GA-EP45-DS3L, $85 after rebate
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128345
If you're not interested in overclocking, you can find cheaper RAM than that G.Skill.
CORSAIR 4GB (2 x 2GB) 240-Pin DDR2 800 $25 after rebate
http://www.newegg.com/Product/Product.aspx?Item=N82E16820145184
Compared to transmaniacon's list, this goes like this:
- overclocks less well
- 10% slower in applications that use only one or two cores
- costs $18 more
- no Crossfire/RAID/FireWire
- no support for 3 or 4 monitors, just 2
However, if you are the kind of guy who runs several things in parallel, or if you like FSX or GTA4, or if you use multithreaded applications for work, or you rip DVDs or CDs, it will be almost twice as fast.
It totally depends on what you need.
You can also combine GA-EP45-UD3P with Q9550 and the cheaper RAM (total 115+280+25=420). There's also a GA-Ep45-UD3R, a little cheaper than the GA_Ep45-UD3P, and you lose Crossfire but gain $10 and a third PCI slot.