I have put together this setup for a gaming and media production dekstop. I have a midrange budget. But if i can get a lot more bang for the buck or significant improvements, i have another 800 USD to spare.

I am slightly unsure of my choice for sli, in varius charts sli seems to be the best performer. And i would like to run multiple screens for video production and 3d rendering. I would also like high graphic settings on 24" display in new games. But perhaps i should simply get a better GPU and a better sli ready Motherboard, and then i would have the choice to upgrade with another gpu in the future?

CPU: Intel Core 2 Quad Q6600 2.4Ghz Socket 775
http://www.newegg.com/Product/Prod [...] 6819115017

GPU: 2 x (sli) BFG NVIDIA GeForce 8800 GTS / 400 MHz / PCI Express 2.0 x16
http://www.newegg.com/Product/Prod [...] 6814143119

PSU: Zalman ZM850-HP 850 Watt / Intern / AC 115/230 V / 47 - 63 Hz
http://www.newegg.com/Product/Prod [...] 6817379007

RAM: mushkin 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) Dual Channel
http://www.newegg.com/Product/Prod [...] 6820146785

Motherboard: MSI P7N SLI Platinum LGA775 Socket / NVIDIA nForce 750i SLI / 1333 MHz / ATX / DDR II SDRAM
http://www.newegg.com/Product/Prod [...] 6813130159

Hard Drive: Seagate Barracuda 7200.11 500gb / 7200 rpm / 32 MB / Serial ATA-300
http://www.newegg.com/Product/Prod [...] 6822148288

Soundcard: Is it worth buying an external? If so can you reccommend a model.

Fans: the current case has space for a 120 mm and five 80 mm fans. How important are the extra fans and do you have some reccommendations?

Should i get an aftermarket GPU cooler?

I have a few components i imagine i can reuse from my old setup:

CPU Cooler: ZALMAN CNPS7700-CU 120mm 2 Ball Cooling Fan
http://www.newegg.com/Product/Prod [...] 6835118115

Case: Chieftec bx-02b-b-sl
http://www.chieftec.com/bx-02b-b-sl.html

DVD/CD drive/burner: My current aopen drive seems to be alright. However can an old drive be the bottleneck in a new system? Should i consider a new one? Suggestions for a model?

Looking forward for your advice!

Looks good, but would change a few items.

First off go with one of these 2 PUS's below, since they should fit your case.
PC Power & Cooling Silencer 750 Quad (Red) 750W EPS12V Power Supply 100 - 240 V UL, CE, CB, RoHS - Retail $149.99
($119.99 after $30.00 Mail-In Rebate) Free 3 Business Day Shipping.
http://www.newegg.com/Product/Prod [...] 6817341011

CORSAIR CMPSU-750TX 750W ATX12V / EPS12V Power Supply 100 - 240 V UL, CE, CB, TUV, FCC, CCC - Retail $129.99
($119.99 after $10.00 Mail-In Rebate) Free 3 Business Day Shipping
http://www.newegg.com/Product/Prod [...] 6817139006

Next you should go with one of these CPU Coolers', would check which one fits your case (Height wise).
XIGMATEK HDT-S1283 120mm Rifle CPU Cooler - Retail $36.99
http://www.newegg.com/Product/Prod [...] 6835233003

and you will ned this for the Xigmatek to prevent the MB from binding.
XIGMATEK ACK-I7751 Retention Bracket - Retail $6.99
http://www.newegg.com/Product/Prod [...] 6835233019

OCZ OCZTVEND2 120mm Rifle CPU Cooler - Retail $49.99
http://www.newegg.com/Product/Prod [...] 6835202007

This one if height is a concern with case you are using.
OCZ OCZ Vendetta 92mm Ball CPU Cooler - Retail $34.99
http://www.newegg.com/Product/Prod [...] 6835202005

Also you will need some good thermal compound, this one is the top rated at the moment. OCZ OCZTFRZTC Freeze Extreme Thermal Conductivity Compound - Retail $6.99
http://www.newegg.com/Product/Prod [...] 6835202006

Since you want to go SLI, I would suggest this motherboard. Since they have lastest Bios out to fix the Video corruption problem of the nVidia chipset. Plus 2 full 16x PCI express slots.
EVGA 123-YW-E175-A1 LGA 775 NVIDIA nForce 750i FTW SLI ATX Intel Motherboard - Retail $189.99
http://www.newegg.com/Product/Prod [...] 6813188026

But IMHO I would go with the GIGABYTE GA-EP45-DS3R LGA 775 Intel P45 ATX Intel Motherboard - Retail $149.99
http://www.newegg.com/Product/Prod [...] 6813128344

ABIT IP35 Pro LGA 775 Intel P35 ATX Intel Motherboard - Retail $179.99 ($149.99 after $30.00 Mail-In Rebate).
http://www.newegg.com/Product/Prod [...] 6813127030

Get the Intel Core 2 Quad Q9450 Yorkfield 2.66GHz 12MB L2 Cache LGA 775 95W Quad-Core Processor - Retail $339.99 and it has 12MB L2 Cache insted of 2x4mb cache of the Q6600 and has Free 3 Business Day Shipping.
http://www.newegg.com/Product/Prod [...] 6819115017

By going with either the Gigabyte GA-EP45-DS3R or ABIT IP35 Pro, you could drop the the BFG NVIDIA GeForce 8800 GTS graphic cards and get one of the new nVidia G280 1gb 512-bit card that is dues out in a week or so for roughly the same price.

Good Luck on your upcoming Build.

Good Lord Yoosty!

Reminds me of the "too much information" commercials

You might choose the Q9450 that Yoosty recommends because it has the new SSE4 instructions. These are apparently used in some rendering programs, of the sort it sounds like you might be planning to use.
Microcenter may have it for $299 + $6 shipping though, so check there. That's where I got mine.

Thanks for the comprehensive advice Yoosty!

This sounds like a good solution, do you have any intel on when this will be available throughout the world? I am located in Europe Denmark.

You reccommend two other CPU coolers, ive seen them recommended multiple places so they are probably a good choice. However is there anything wrong with my current zalman cooler?

jtt283: In rendering i will be using blender with Yafray. And il be doing a lot of development in Second Life.

What about a soundcard. Any suggestions?

None of the intell motherboards will do SLI.

Intell=crossFireX.= 2xATI Video cards

The nVidia G280 is being Officially Launched on June 17th, 2008. So figure they should have them out in a week after that. Also Gainward had one on displayed at Computex 2008 and I know they are sold mainly in Europe.

The top two Sound cards that I would recommend are the following Brands. Asus and Creative, both using a PCI-E 1x slot. Asus will have a new card coming out in July that will also be HD compliant. Also Creative just came out with a new PCI-E 1X. I do not kow if they are available in Europe yet, but if they are you could find them at one of the floowing sites in the UK.

Has both Asus and Creative in PCI-e 1X
http://www.scan.co.uk/
http://www.overclockers.co.uk/index.php

Has either Asus and Creative in PCI-E 1X
http://www.dabs.com/homepage.aspx
http://www.ebuyer.com/

Below NewEgg links are for your viewing of PCI-E 1X Sound Cards.
http://www.newegg.com/Product/Prod [...] CI+Express

It could be fine, but in case Temps do run hot I would suggest you keep the other two CPU Coolers in mind as a replacement.

Hope this helps you out some more.