I've tested DLA 5.20 and Sonic Drag-to-Disc 9.05. Neither one will allow XP to write to a UDF formatted hard drive. I have not yet tested InCD, but my guess is that it won't work with hard drives either.
The only product I've seen so far that claims to write to UDF hard drives is SAI's WriteUDF!, but it's $80.
There's also the free DVD Write Now, but I doubt it will work either. The last time I tried it, it wasn't the most stable thing in the world (not good for a program that has a filesystem driver component), and it only claims to handle UDF 2.01 writing. I'm not sure whether or not that would prove problematic.
The route I've gone personally is NTFS, along with putting the NTFS-3G for Mac installer on the hard drive. Since OS X has read-only support built in, this works well.
If you want free, cross-platform, and no file size constraints, NTFS is going to be your best bet. NTFS-3G for Mac is free and performs "well enough." The company backing the free NTFS-3G also sells Tuxera NTFS for Mac, which is supposed to be much faster. There's also Paragon's NTFS for Mac software as well, but it's not free either. At least there are options.
Ext2 will also work, and there are free drivers available for both Windows and Mac, but you have to have a secondary method of getting the drivers onto your host systems. This is also a problem for NTFS and Linux. I don't know what performance or stability of the various Ext2 drivers is like.