You can get coolermaster 4in3 units that I think fit in normal PC's too. Other then that, there are plenty of 3.5" in 5.25" bay adaptors in most online shops case sections. There are ones designed to cool available also but they cost around £20 and up.
http://www.scan.co.uk/Products/Prod...ilterMaxPrice=&FilterCategories=273&OrderBy=1 Some things there. Really, just look in case or HDD sections of online shops...I'm not sure I can make it any simpler then that.
cheers, thanks alot, just found some on e-bay click here this be good as my cd-rom Drive in the 5.25 bays are on screew roll