I once purchased a Packard Bell which worked fine for a while but then I wanted to upgrade the HD. What a nightmare PB do something called a tattoo to the HD so the software disk will only work with the original HD. Eventually after much blood sorted it until I wanted to tweak it some more - impossible. It seemed that branded systems are not designed to upgrade / change / add to etc so it was skipped and went down the home build route. I also thought I had the OS from the PB but it turned out PB only licence the software to the machine so the user has no rights to any software if the machine dies so I vowed never to touch a branded system again. However, if you do go the branded way make sure the OS original install disks are included and not bundled.
I just built another - took about 4 hours & its great I used Scan Computers who were brilliant and good on price
Good Luck