xbox360 hard drive mods

Hi,
as any one upgraded there xbox 360 hard drive to none xbox hard drive?
got a programme and sort of know how to do it,just need to know what hard drives can be done on the cheap.
im thinkling around 120gig hd but i will be happy with 80 gig.

am i better off just buying the 120 gig xbox hd for 60 uk?

tbh i think xbox will release a bigger hd as you can now store games to hard drive,so would i be better off getting like 320 gig hd and waiting for the bigger xbox hd release so i can un lock more gigs on the 320 gig?

thats what i would really like to do but need to know the hard drives that will work if any one can help i would really appreciate it.

thanks in advance.

ps what are the cheapist hds you can buy over 120gig in the uk?
thanks