Just as a basic install.... 2gb? less? Thanks.

2-3GB at a guess, but dont forget small HD's have a slooooow access time so folding will be impeeded by the paging file and its own checkpoints. I would look at a 40GB minimum, well you cant buy much smaller these days.

The Windows directory can start at as "little" as 500mb but it can easily swell up to a couple of GB quite , then you'll have a page file that can be a couple of times the size of the amount of memory you have as well.