After 3.1 ROMs and OS3.9 the HDD issue is more down to ide interface then anything else. On a standard A1200 you will need to partition into multiple logical drives(as said previously on this thread)with any drive over 4 Gig.
If you use a 3rd party ide interface with support for larger drive sizes (such as elbox's 4xEIDE '99) you can use disks larger then 128GB.
Are you keeping the wedge or going for a tower? that's the first question for me as it decides so many other issues, space, heat, power etc.
Anyway, your in the right place. There are some smart people on this forum, even if I don't allways agree with them.
:lol: