Here’s the link to the thread in the FAQ section of the forum: Moving WD to a new/different PC
WD does run on Windows 7 64 bit and does run on W8, but not sure where it’s been tried on both 32 & 64 bit.
The WD version you are running is very old, in WD terms, and there have been quite a few updates since that came out. It may be better to download the latest version into your XP machine and see what happens, before loading everything on to W7. At least that way you can make sure it’s all working before the transfer and you can rule out the software update as a possible cause of any issues you may find after the transfer. 
As for the RS-232, you will probably need a Serial to USB adaptor for the new PC, unless you’re fitting a Serial PCI card to the motherboard. In which case make sure it’s a good quality adaptor and has the latest drivers installed.
The best advice if you don’t want to lose any data is to backup backup and backup again. 