I asked this question over at MandrakeExpert when I was partitioning new drives. Although it won't help you too much with drives that are already formatted in a different filesystem, you could (with enough room,) format a new drive and move all the stuff in a "three-point" move. (Old drive -> Middle drive -> New drive)
Here's what I was told:
If you store your data on NTFS, you can read them from Linux, but not write to
them (the option is present in the kernel configuration, but that's still
experimental (= very dangerous)).
If you store your data on ext2, you can read them from MS using for example
the free ltool software (don't expect Microsoft to provide you with something
that would admit that there are other OS's in this world). There is a write
option, but I wouldn't take a chance using it (too dangerous).
If you had a FAT32 partition, you could read/write from both Microsoft and
Linux. However, I did try that in the past but finally got rid of the
partition because I was spending all my time trying defragmenting it.
I would suggest you to put your data on NTFS. You will have full read access
from Linux, much better that ltool can provide for reading ext2 from NTFS.