150mb in a week is a lot. that's unlikely to be browser caching or index.dat files (which are text anyway and take up a few kb at most) and I'd tend to say that's your media player (iTunes) hogging the space there, it's the only thing from what you've told me is on your pc that could be using up that amount of space in such a short time.

I suggest you call me on the secure channel to Tawakalnistan and I'll tell you how to deal with the stupid thing. Alternatively you could contact the Hare but he makes everything far too complicated and I'm better at this sort of thing anyway!

I heartily recommend CCleaner, it's free and recovers large amounts of space that are being used for nothing important or necessary, and it fixes lots of registry issues as well - although be careful how you set it up, by default it wipes all your cookies off as well (it stands for "Cr*p Cleaner" btw)

I may have to take you up on your offer, Taw. The forces of evil seem to have claimed another 400mb so far in the last ten days. There's been only one installation of less than 100 mb, no other new content. All the temp folders have been emptied. I've pulled down the file size for system restore and even reduced the amount of virtual memory. Still no joy. If iTunes is indeed the culprit, I'll have to go rearrange all my songs into mp3 format, find a 3rd party iPod interface software, and kick the bad guy overboard, because this is just getting rediculous.