jamok99,
I'm not sure of the uses of your system and performance expectations, but where a Q6600 at 2.4GHz has gone before, a QX6800 - that = a Core2 Quad Extreme at 2.93GHz should work.
http://ark.intel.com/products/30720/Intel-Core2-Extreme-Processor-QX6800-8M-Cache-2_93-GHz-1066-MHz-FSB?q=QX6800
http://www.ebay.com/itm/Intel-Core-2-Extreme-QX6800-2-93GHz-SLACP-G0-Quad-Core-LGA775-Processors-/400808536831?pt=LH_DefaultDomain_0&hash=item5d520ceaff (Ebahh completed listing ffor $85)
These older systems with upgrades can have respectable performance. I was recently given a Dell Precision 390- same socket and series as Q6600- and spending about $125 (I had the Firepro V4900 lying around):
Precision 390 (2006) Original : Core2 Duo 6300 @ 1.86Ghz, 2GB DDR2 ECC 667 > Quadro FX550 Passmark system rating =
397, CPU = 587 / 2D= 248 / 3D=75 / Mem=585 / Disk = 552
Dell Precision 390 Revised : Xeon x3230 quad core @ 2.67GHz > 6 GB DDR2 ECC 667 > Firepro V4900 (1GB)> 2X WD 320GB > 2X Dell 19" LCD > Windows 7 Professional 64-bit [Passmark system rating =
1458, CPU = 3642 / 2D= 433 / 3D=1346 / Mem= 853 / Disk=582]
Notice the important change in the 3D score from 75 to 1346. In Passmark baselines, the
highest 3D score for a Firepro V4900 is 1453. The 1346 is probably about No. 40 of 168 scores, but this means that these systems can get up the steam in a decent GPU.
Also, using the full capacity of the RAM- 8GB?, and a BIOS update should produce a positive result.
You could also get a big boost by changing your OS/Program drive to an SSD and the new Crucial MX100 series makes this inexpensive:
http://www.superbiiz.com/detail.php?name=128GMXSSD1
Cheers,
BambiBoom
HP z420 (2014) > Xeon E5-1620 quad core @ 3.6 / 3.8GHz > 24GB DDR3 ECC 1600 RAM > Quadro K2200 (4GB)> Samsung 840 SSD 250GB /Western Digital Black WD1003FZEX 1TB> M-Audio 192 sound card > AE3000 USB WiFi > HP 2711X, 27" 1920 X 1080 > Windows 7 Ultimate 64 >[Passmark Rating = 3949 > CPU= 9222 / 2D= 835 / 3D=3553 / Mem= 2573 / Disk= 2118]