Any higher-end CPU you buy will be faster and more technologically advanced.
The choices are the Phenom II X4 955 ($165), i5-750 ($200) or the i7-920 ($290). The X4 is a great budget choice, the i5 is excellent for mid to high end gaming and the i7 is great for multi-tasking, CPU intensive uses and high end gaming.
$800 is a huge amount for those parts. You can easily afford the i7, a USB 3/SATA III board and RAM. This would be a very high-end system:
For you're uses, you should use the i7. It's better for pretty much everything except gaming.
As far as the difference between Mushkin and Corsair RAM, it's mostly price. Over here in the US, Corsair is vastly overpriced. Basically, you should be looking for CAS Latency 7 (timings 7-7-7-x). Speed isn't as important, and usually 1600 mhz is more expensive with higher timings. Brand isn't important at all. The big names are G.Skill (harder to find outside of the US), Mushkin, Corsair, and OCZ. All of these will have about the same quality and offerings.
You might want to consider getting two sets as Photoshop can take up a lot of RAM, but buy whatever you can afford.
I can get 4 Gigs of ram (Im running Windows 7 32 Bit) with the timings you mention for about 150 $, and with the board and the cpu (and cooler) it will be about 780$ and thats ok. And i dont do gamimg at all, so i guess i can keep my Radeon 4770.
Thank you very much for your help, ill go for the i7 920 and the Asus P6X58D Premium you recommended, and then ill buy some ram with 7-7-7-x timings
One problem with 4 GB of RAM: the i7 uses triple channel, meaning 3 sticks. It will not perform as well if you use 2 (or 4) sticks of RAM. I'd recommend getting a 3x1 GB kit, since you're using a 32-bit OS.
I'd highly recommend you look into getting a 64-bit for what you're doing though...
The rebate dosent matter at all cause ill have to buy my ram in Denmark(where i live) thats why i ask MadAdmiral if Cosair ram was just as good ! and which would be the best choice
But thanks for your reply !
I could get these Cosair ram timings: 8-8-8-24 77$ cheaper, but ill rather go for the ones you recommended. Yesterday i bought the motherboard and the Cpu, and now ill buy the OCZ Platinum DDR3 7--7-7-24.
A big thank to you MadAdmiral for helping me all the way