Will 64 bit partition read 32 bit partitions?

Yes!

By the way 64 bit version has nothing to do with the formatting of the HDD but with the type of CPU that is required to run the OS.

HDD under Windows are usually formatted either NTFS or FAT.

Like emerald says, 32bit vs 64bit has nothing to do with the drive. I've in the past had 32bit XP and 64bit Windows 7 running on the same HDD, with no problems.

Check your OS very closely, because some 32-bit versions
cannot address partitions larger than 2TB e.g. Basic Disks
under 32-bit XP.

64-bit versions can easily address more than 2TB.

Also, if one does not need to boot from such a partition,
some third-party RAID controllers allow Variable Sector Sizing
("VSS") e.g. Highpoint, which will permit partitions to exceed
2 TB under XP 32-bit.

The problem is complicated by permutations varying by
OS version, RAID type, and 32-v-64 bit logical addressing:

http://technet.microsoft.com/en-us/library/cc773268%28W...

http://www.tomshardware.com/forum/229369-32-problems-la...

RTFM (Read The Fine Manual -- not always "F"ine, however  


MRFS