Computer Advice

Hello,

I know this is a photography forum, but I'm looking for some good computer advice for photo editing use. I plan on mainly using Photoshop CS4, Adobe Bridge, PhotoMatix... and iTunes going in the background. I want fast, but trying to keep my budget around $1000-1300 CDN.

Anyone's experience would be helpful!

Chip:
-I'm trying to decide between Q6700 vs i7 920

The i7 920 system is about $300 more than the Q6700, so I'm wondering if it's worth it. I've seen some charts that show Q6700 works just as fast i7 920 with Photoshop CS3, but I'm not sure about CS4.

I've read reviews from people who are using the i7 920 and say it's blazing fast with Premiere and Photoshop, but I don't know what they're comparing it to.

GPU:
-Radeon vs. Nvidia??

I've read lots of other photo editors are using Radeon, but not sure why. Nvidia claims to have utilized CUDA technology with CS4, but other reviews say that this is rubbish.

Any advice is appreciated!

Cheers.