No need to reinstall. You can resize your existing partitions by booting an Ubuntu Live CD/USB and using the Gparted Partition Editor (under your System menu).

It is prudent to back up your data (on both Windows and Ubuntu) prior to resizing.

According to the link below, 15gb is the recommended minimum for Ubuntu:

https://help.ubuntu.com/community/In...emRequirements

Thanks guys - all useful posts! FTR I chose to get into Linux (Mint) primarily because I didn't want to buy an extra 512mb ram for my 7 year old satellite pro. Buying more ram (not cheap on these old machines) I may just as well have stuck with microsoft xp which would probably then actually run ok duh! Now the talk above is that if I wanna stay longterm with Linux that I ought to be getting out the credit card for additional ram for the laptop after all! PS Still running xp on my much better spec'd desktop machine but I'm liking free Linux and thinking of the 'donations' I could make if I don't buy the ram

Any OS will run better with more RAM. Linux with all the bells and whistles enabled will run slower, as will XP with pre-install junk (and toolbars, preloaders, spyware, etc).

It's just a matter of perspective.