TD - if you intend to install W7 AND keep XP as well, you will need to partition your drive and install the new OS in a different partition to XP. As bf says, 30gb for each would do for starters - difficult to comment on P Magic since you do not say which version, but again as BF says, Easeus is a good tool. Partitioning is very straightforward with the modern software and makes backing up routine stuff easier.