Thanks - this is making more sense now. A final couple of Q's before I go buy:
I've decided to scrap the gfx for the moment. The onboard gfx will surely perform OpenGL acceleration and the input of the GPU compared to the CPUs will probably be minimal. If I find gfx lacking I can always stick in a card later.
I'll also not worry about HDDs for the moment. Again, I can keep the cost down now and add one later, simply relegating the current HDD to a 2nd drive.
If I don't add an HDD I'll need an e-sata connection for the 1TB Seagate Extreme drive. I take it these are add-on cards and not something I'm likely to use once USB 3 becomes prevalent. Am I maybe better off cracking open the Extreme drive and just putting the HDD in the machine? Sounds a bit... extreme (groan)... but worth a look?
I can use some of the saved money from the extra HDDs and Gfx to put on 8GB RAM to start with - thanks for the tip about the speed not being of upmost importance.
I think the only point I'm umming and erring on is the dual/quad core debate. Firstly, is the ASROCK K10N78M good enough for a quad core? It looks quide diddy:
http://www.asrock.com/mb/overview.asp?Model=K10N78M
only 2 RAM slots and 2 PCI. I'm not even sure what the green and little white slots are... they didn't have them last time I bought a PC
If I use one PCI slot for an e-sata card, I've only got one left, and I might have to install a wireless networking card for internet in my new flat... Can I get a bigger board for around the same price?
And finally, bearing in mind that I do a lot of multi-tasking and will generally have msn, skype, outlook, LR2, PS4 and a couple of little photo-apps open at the same time, am I right in saying that the quad-core will be a lot smoother overall, even if it won't 'out-benchmark' the dual core?
Cheers again!