you wouldnt get any performance increase if you was to switch to windows 8
the pc is ok, but i would only use it to browse, open documents nothing else.
you can maybe use 1gb of your ram as ramcache or ramdisk to speed up your pc. i have a 4gb ram athlon x2 pc (only use it for surfing n opening documents) i use 1gb for ramcache, it feels alot smoother.