cat5e will be absolutely fine, don't make the mistake though if plodding down to somewhere like pc world, asds or any other retailer, they are an absolutely rip off. You can get good quality branded cables from places like play.com or amazon dirt cheap with free delivery.
As an example, if you have a look at PC World, a 15m belkin cable costs £35
http://www.pcworld.co.uk/gbuk/belkin...19297-pdt.html
On Play.com it is £9. You can get a 30m cable for £16. It is a joke really, twice the distace and nearly £10 cheaper.
http://www.play.com/Search.html?sear...0M+Patch+Cable