Well what's happened was the thing infected all my .dll's .exe's .htm's and .html files; basically it was copying itself faster than sophos could handle (or some similar business that kept it alive). Even in safe mode it was doing its business, and sophos couldn't find the source beyond it residing in the memory and the explorer.exe.
It infected upwards of over 6,000 files and after culling 2,000 thousand it re-infected 1,500 of what had just cleaned on the move. By the time i ran another scan, all the files were infected again.
Oh well, the benefit was it finally got me around to buying a new system (even though the store gave me the wrong M-B and wasted half my day as the CPU wouldn't fit).
I got a GTX-460 with an i7 930, 2x 500GB HD's, 750W PSU and 4GB RAM. Hopefully settling for the cheapest compatable M-B wont put me out, it's still a pretty decent piece of hardware i suppose.
I still got my old computer... i need some data off it, such as my FF bookmarks, level design and uni work etc. Once i've done that i'm just gonna re-format the bitch and flog it to a needy mate to ease my sore wallet. Nothing wrong with it besides a GPU that's seen better days and a bit of dust.
Will be a while before i have the system up and running with all the required software. I had £3k sitting in my current account, now it's 800 less, plus i wanna get Adobe CS-5. So much for chilling out on those saving for a few more months, gotta get me a job ASAP.
@ Rexy
Sophos listed the threat as low, even though Semantec said its damage is high. Even though it wasn't damaging my system per se, it was eating a lot of memory and was generally annoying, supposedly it hunts after banking information, so it's a major security risk. It appeared to be a hybrid of a much larger trojan from 2 years ago. So this was a pretty significant problem for me to deal with.
The last infection i had i managed to cull by finding the source (by purposefully crashing my computer, as the fucker was managing to close my task manager so i couldn't stop the process), even though sophos wouldn't/couldn't touch it as it was active i managed to manually remove it (somehow). This one however persisted in the memory and infected my registry. I'll have to admit defeat to this one and just blitz it with a format.