I found another series of benches that might help the OP decide. Here's the 5870 on a few cores... not many, but enough to get a better idea.
At 1280, obviously, the i7's just kick butt with the 5870, but as res increases we can see things even out a bit. Granted, they didn't test a Q6600 (those are hard to find these days), but I think we can safely assume its results to be somewhat similar to a Core 2 Duo at 2.75GHz... not exactly the same, but very close.
May Power Be with You: Find the Best CPU for a Single ATI Radeon HD 5870 and ATI Radeon HD 5870 CrossFireX Configuration (page 6) - X-bit labs
Pages 5-8
At 1280, obviously, the i7's just kick butt with the 5870, but as res increases we can see things even out a bit. Granted, they didn't test a Q6600 (those are hard to find these days), but I think we can safely assume its results to be somewhat similar to a Core 2 Duo at 2.75GHz... not exactly the same, but very close.
May Power Be with You: Find the Best CPU for a Single ATI Radeon HD 5870 and ATI Radeon HD 5870 CrossFireX Configuration (page 6) - X-bit labs
Pages 5-8
My Computer
At a glance
7 Ultimate x64i5-2500k8GB G.Skill Ripjaws X F3-12800CL7D-8GBXH 1866...EVGA GTX 570 SC
- OS
- 7 Ultimate x64
- CPU
- i5-2500k
- Motherboard
- Asus P8P67 Pro
- Memory
- 8GB G.Skill Ripjaws X F3-12800CL7D-8GBXH 1866MHz 8-9-8-24
- Graphics Card(s)
- EVGA GTX 570 SC
- Sound Card
- X-Fi Titanium Fatality
- Monitor(s) Displays
- Samsung S27A550H 27" LED
- Screen Resolution
- 1920x1080
- Hard Drives
- OCZ Vertex 3 120GB.
1TB Samsung F3.
2TB Samsung F4.
- PSU
- PC Power & Cooling Silencer 760
- Case
- Lian Li Lancool K62
- Cooling
- Thermalright Venomous X Black/Scythe S-Flex/Shin-Etsu X23
- Keyboard
- MS Natural Elite 4000 Ergonomic
- Mouse
- Logitech G500
- Internet Speed
- 6MB/768
- Other Info
- Logitech Z-5500 505 watts.
D-Link DGL-4500.
Tripp-Lite Smart Pro 1500.
haha