If you need extra storage you could put a larger drive in albeit it voids the warranty.
If going down that route, make sure you put a PVR specific HD in and not a pC one otherwise you'll have power and heat problems.
I put a 1TB WD PVR Specific HD in mine about 2 months ago and it works great!
Is this fairly straighforward for anyone used to messing around inside computers Alsone? My humax hdd is filling quickly with HD! Photos or mini-guide would be great
Sorry to go slightly off topic from the OPIT's very easy, upgraded mine also....if you head over to www.digitalspy.co.uk
you'll find plenty of threads on the subject, in fact try this one