couldn't use testdisk - os wont boot with bad hdd!

then i have getdataback, and ntexplorer.

Seatools from seagate is just for disk diagnostics - it can repair hdd bad sectors (actually it remaps the sectors i think so i left it alone - dont want to replace the data right?)

i dont have any blank hdd or blank dvds, so i'll be getting one more 500gb hdd this week - hopefully not seagate!

so my situation is this - if i get a new hdd (which i should to recover data) i will have it installed in my machine together with my bootable hdd. now if i try to be smart and add the bad hdd, then the os wont boot - so i'm thinking of getting an external case so that i could get a chance of using testdisk / gdb.

anything more u ppl could think of?