Just for the hell of it since I'm bored (sorry for DP but it'sbeen like 6 hours ) I figured I'd throw you a list of which processors to look at depending on which line you choose. (In most cases out of the multiple processors in each catagory only 1 is really worthwhile)
Intel Core 2 Duo:
E8400 Duo 3.0/6mb > $168 Probably the most popular processor on newegg right now. The Core 2 duo comes in higher clockrates, but as with most intel processors nowadays, it makes much more sence to buy the cheapest in the line then overclock it a tad than to pay for a higher default speed.
Intel Core 2 Quad:
Q9550 Quad 2.83/12mb >$230 Same note as with the Core 2 duo, buy the cheapest full featured version and dial it up if you need more speed, the $100 more to step to the 3.0 version is crazy.
Note on Core 2's. the E5xxx, E7xxx, and Q6xxx & Q8xxx lines of core 2 are scaled back versions, that is why we go with the e8xxx and q9xxx lines
i7 920 2.66 > $280 As with other intels, the cheaper version is the way to go. (This one even more so because of crazy price jumps)
AMD Phenom 2:
x4 940 3.0 > $190 Unlike Intel, with AMD we aren't going with the cheapest Phenom x4, rather the cheapest phenom x4 'Black Edition.' because of the much closer price groupings with AMD processors, getting the black edition for an unlocked multipler for even easier overclocking is a no-brainer. As far as the AM3 version, IMO it's not worth it. DDR3 kicks ass with the i7 because of tri-channel, for AMD save the $ and put it toward a better video card.
Here's a good motherboard to go with Either the Core 2 Duo or Quad:
EVGA 750i >$146 Theres a $30 mail in to bring the final cost down to $116. There many motherboards you can choose between, this is just 1 from a good brand that should have what you need + a little room to grow. (this note applies to all Motherboards)
And one for the i7:
EVGA X58 >$240 This 1 is different than what I linked before I think, but digging through them tonight all the cheaper i7 boards had something I didn't like. (Either brand, no SLI support, or only 4 channel for RAM) This 1 is the least expensive option that seems to cover all the bases. (I realise you aren't doing SLI now, but keeping you options open is never bad)
And for the Phenom 2:
Asus 750a > $135 Again, SLI just in case as with others.
And finally some Compatable RAM:
For Core 2 Duo/Quad or Phenom 2:
G.Skill 4GB Kit > $55 There are a few cheaper kits to be sure, but I prefer the 4-4-4-12 timing kits to the higher lattency memory. This is 2 2gb sticks so if you want more than 4GB RAM just buy 2 kits.
And RAM for the i7:
OCZ 6gb Kit > $110 Think this is the same kit I linked before, but it's $10 more initially, with a $20 mail in rebate now. 3 2GB sticks here, so if you want more than 6GB just buy 2 kits again.
Everything else is basically universal unless you go out of your way to buy non-standard stuff. As I said earlier, just stick to PCI-E, SATA & ATX and you'll be fine for the rest.