I currently have a Packard Bell Imedia X2414 and want to change the case to this one - http://www.ebuyer.com/search?q=Casecom L… - will their be any issues in swapping the components over. I.e. will i need a larger power supply etc

Answer:
In theory no problem, you're changing your power supply over and all the case is is a box that keeps the dust off the internal parts.

Packard Bell have a nasty habit of welding parts, so do a dry run disassemble before buying the new case. If it comes apart no problem it will reassemble no problem.