sd ram question

I am not sure if this falls on this forum or not.....But I would like t oupgrade my desktops, I was wondering first how to determine the max capacity of sd-ram...Also curious if I was to upgrade hard drives, could I somehow transfer my O.S. I am currently running xp home and do not have the disks..There is a license sticker on the side of the tower(if I obtain disks could I re-install in a new hard drive?) I do not even know if that is worth doing to these, would I have to upgrade everthing or can you make a difference with sd-ram and h.d.

 

To find out how much RAM your system can take, you need to find out the make/model of the motherboard (or if it's a mass market PC like Dell or HP you need the exact model) then visit the manufacturer's web site and look it up. Or check the motherboard manual.
There are many utilities that allow you to copy an entire hard drive to another, so the new drive will boot when connected to the PC that the old drive was connected to. Most of the hard drive manufacturers have these programs for download on their web sites; sometimes the software is included when you buy the new hard drive. Alternatively, there are several good free programs available here at Major Geeks in the Back Up downloads section.