^^ L3 cache memory tips the ball-game in your favor in real-time scenarios like gaming, 3Ds Max, MAYA and other such heavy applications, for you I would suggest this slightly more upto scratch rig
AMD Phenom IIx4 955 / 840 ~ 6200/-
OR 5200/- (the Phenom IIx4 840 has no L3 cache, so strict no-no if you'll use system for gaming or other heavy applications consider it seriously only if your budget pulls up short)
Gigabyte GA-880GM-UD2H ~ 4400/-
G.Skill Trident 1600 MHz CL-8 4GB kit ~ 3000/- (this is a steal deal, go for it eyes closed, following is verifying link) --
G-SKILL[ Trident ] PC3-12800 / DDR3 1600 Mhz/cl-8-8-8-24 (2Gx2)
Sapphire HD 5770 ~ 7000/- (I recommend this over the MSi HAWK edition as I've had manufacturing defect issue with a MSi HAWK 5770,
but this was promptly RMA-ed)
Gigabyte Superb 460W ~ 1900/- (reliable, stout SMPS this one)
This rig should be a bit better balanced in lieu of the old first generation Phenom IIx4 945 you were buying although note these have L3 cache which the Phenom IIx4 840 lacks. Some links that might help you --
AMD Phenom II X4 840 3.20 GHz Review - Page 12/12 | techPowerUp
CPU cache - Wikipedia, the free encyclopedia
Core i3 SB beats pretty much most/all AMD quad cores, or at least more or less equals them. Go for an entry level board with 4 GB RAM and a PSU you can afford. It will easily fit in under 20k.
Not much sense in a world being multi-threaded, which allows the Phenom IIx4 to keep going after being so old. Plus the Phenoms can easily be over-clocked not quiet possible with the Sandy-Bridge till you get the P67 / Z68 boards which ramp up the cost to ~ 25000/- ++.
AnandTech - Bench - CPU