Re: Hard drive question
Installing the drives is just a matter of finding an open bay that works for your cable lengths and airflow. Ideally you want some air flow over your drives, so set them where air can pass over or by them. Hard drives today aren't so much failure prone to heat as some people might assume, but it doesn't hurt.
The setup I would use is to connect the two drives you mentioned that are new, and install your new operating system on to that drive, and use your old XP drive for archive storage duties. The advantage to this is that you don't need to do anything to the drive but plug it in and start using the files off of it (media, photos, etc) but booting to it would be a bad idea, as Teny suggested, because the new motherboard likely won't work on the old XP install - it's just too much of a headache in most cases, so you're almost always better off by going with a fresh windows install, and if you're going to do that, do it on a newer [and likely faster] drive, like the one of those two you're buying.