Apart from the well-documented benefits of Ubuntu/Linux over windows, for me there's now a matter of principle: a machine with pre-installed windows is generally stuffed with bloat-ware. I recently bought an Acer Aspire with Windows 7 starter. It was riddled with anti-virus bollox and stuff for ebay, aol, BT etc etc. It's faster just to bung on Ubuntu then bother taking all this stuff off.