the only thing i would recommend is, once you’re using windows 7 just make sure you have the service pack 1, unreal doesn’t works in windows 7 without the service pack.
if you’re not sure if you have or not service pack 1 installed, just go to your control panel and then click in “system”, if you have SP1 installed it will show “service pack 1” under the “windows edition” tab, otherwise it will just show “windows 7 ultimate (or professional or whatever) copyright…”
if you don’t have the service pack you can download it here:
https://www.microsoft.com/pt-br/download/details.aspx?id=5842 (the file you’re looking for should be windows6.1-KB976932-X64.exe supposing you’re using a 64 bit version)
you can also download it through windows update
if you have SP1 and still have trouble i don’t know how to help you