how much you got?
seagate have been getting good reviews lately
but everyone who answers will give you a different opinion.
look in a couple of computer mags ... see what they recommend
or decide on a price ... and buy within your budget.
discs are pretty much the same (you need some pretty sophisticated gear to measure the differences which are pretty small)
if you are dual booting (remember oldest os first) say XP and vista
your system drive (c:) need only be 20 - 32Gb, your second os is vista ... that partition needs about 50Gb
then you can use a third (big) partition for storage
the alternative is to use virtual pc (free from
http://www.microsoft.com/windows/products/winf amily/virtualpc/default.mspx)
to run a second, third, etc etc os
I've used vpc for years now ... it's good!
You can also use it to keep your main system safe and virus free by surfing from a vpc