depending on how patient you can be... Intel processor are currently Sandy Brige, with the refresh Ivy Bridge expected around June.
Nvidia is also expected to reveal their latest chip (GK104, should go into GTX600 cards) in the coming days. Of course, in computing, there is *always* something around the corner...
One remark: your current monitor will really limit what you can do. If you expect to game at 1680x1050, any graphic card even in the mid-range will do If you want higher resolution and plan for the future, you'll need higher.
Case: reuse yours. No need to change.
PSU: yours should still be OK, as long as you don't plan to go SLI/XFire
CPU/MB: Core i5 2500K (still the best value, $180 @ microcenter) + Z68 MB (choose board according to features wanted, brand and price. ASUS and ASROCK have good ones. ~$170)
RAM: very cheap. Grab 8GB of DDR3 1600 for ~$40. Can double if you really want to, but usually not needed
SSD: can get a 120GB SATA4 for $100-180 depending on brand and model. Remember that ANY sata3 SSD will yield great improvement from a HDD.. Small differences in bench won't matter in everyday life Again, MicroCenter has OCZ Petrol for $100 AR http://www.microcenter.com/single_pr...duct_id=038196
Intel has the best reliability and the highest prices.
Video/Monitor: Both are linked. For your current monitor, any card <$300 (nv GTX570/560ti or ATI 7870 will be already overkill as they work great at 1080p). I would wait a week to see the new nv chip and how it makes prices move.
Hope this gives you some pointers.