DON'T go for performance over quality when selecting a new computer/ parts. Stability will in the long run save you much more grief than that extra couple of extra Mhtz, or a larger HD - which you can easily learn to work around. Heck, for £1300 you could land yourself a pretty sweet PC, and still have a fair bit to spend on a decent sound card too.

As for the Virus, there are plenty of very powerful VSTis that can emulate most of the sounds you'll find on the TI, though it's certainly nice to have the real deal. Knobs are nice... Dunno if I'd be prepared to fork out that much cash though - I'm not a professional musician (yet), so I have to be sensible.