Ok.
I didn't read that bit.
How old are you dude?
Unless you are using 5D Mark IIs and higher or coding HUGE apps, your current rig is more than enough. Hell a iMac would be enough.
What gives on spending £4k on a MP? :/
BTW, I use a 2.66Ghz Quad Mac Pro with a 4870 for:
1. A 33,000 (20K+ RAW) image library (40D)
2. Aerospace Engineering 3D CAD work
3. 1080p HD video work.
I could have bought a 2.93, lost £360 more (being a student thats really pushing it...) and its perfect. Couldn't ask for more.
So I ask... what are you using it for photography wise?
not much really (beginner nikon d60),i pefer the mac OS my Macbook is faster in most cases than my Windows PC.
i want a main Computer that can be used for oSX/Windows Legally.
i did consider the IMac i really did but its not a choice any more it would be a downgrade in hardware spec even if it was faster, plus my 30" would not work with the Imac & would not want to lose the 30" as i do really like the real estate.
this only leaves the Qaud/Oct option.
i asked for your suggests,which this thread was all about.
the ideal of this computer was to to move to OSX as my main OS with the intention of keeping it for some time (hoping 2-4 or more years if possible)
The Qaudcore may hold that long but the 8GB Limition seems a bit obsurd, now i know of it. specailly as i have 6GB now and can use 2GB-3GB in with all my software open. (vista)
i have worked hard for the money, I also recently got a massive bonus & pay Rise so can afford it quite easily. (heck could be my treat

)
Btw, Im 20
if you want to reconsider your specfication you would buy with these new details you now know of so be it

(you will know more than me what a MP could handle)
i did't really want to spend £5000 pound i really wanted to spend up to £4000 but could stretch to £5000 which is why i asked if it could be done cheaper.
hope it helps
Smogsy