Alright.
I'd recommend going with the cheapest good quality case and PSU in order to maximize CPU and GPU performance. You can go with either an i3 dual core with HT or an i5 quad core - the former could allow you to afford a 7850 2GB which is nice for 1080p, while the quad core would probably last longer before you needed another platform upgrade. The video card is always easier to upgrade.
Mobo Asrock H61iCafe $65
CPU i3-2120 $123 ($115 in
amazon) or
i5-2400 $190 (or
i5-2500 $195 AP, ends today)
GPU HD7850 2GB ~$250 (preferably Sapphire but it's out of stock) or
560 Ti $190 AR
Case Antec 300 Illusion $45 AR AP (if you mind the LEDs, then
HAF 912 $50 combo'd with another NCIX product for free shipping)
PSU Corsair CX500 $40 AR,
OCZ ZS550 $45 AR,
XFX 450W $45 AR, or
Seasonic S12II 520W $70 (if you don't do MIR)
$520 AR with i3 and 7850; $530 AR with i5 and 560 Ti
If you want to spend less, especially without rebates, then buy i3 and 560 Ti or i5 and 6870.
Deals come an go though, so these (cases and PSUs in particular) may not be the best bang-for-buck choices by the time you're ready to buy.
If you live near a microcenter, you could get the CPU for cheaper (i5-2400 $140), and possibly get a discount on the motherboard. I'm not sure which CPU and mobo combos are eligible for the discount though.
Your RAM is DDR3 1333mhz or 1600mhz at 1.5V, correct? How many gigs? And the drives are SATA II (3gb/s)?
🙂