Without knowing what other programs are running in the background it is hard to tell but my guess is you are probally running a little low on ram. Windows XP requires 256mb min. ram to opperate propperley, LimeWire 4.8.1 open not minimized on my computer would creep up to 80mb after about an hour. If you are running Norton antivirus and Norton firewall another 40mb etc. 512mb on a machine running XP is a little weak some times it will run your O/S, office , and other lite applications at the same time but when you start running more memory intensive programs you might be running a little short. You might want to try the new beta 4.9.10 it does not appear to use quite as much memory also when you minimize LimeWire it appears to use less memory. Also I see you are going to be upgradeing your computer the first thing I would do is get another stick of 512 for the money spent it will be your best preformence booster. Then get the new CPU latter because if you get the CPU first you are still going to be a little weak on memory. The link below will take you to 4.9.10 sticky there is a link in there for basic . Pro can be downloaded from your personal download page.
http://www.gnutellaforums.com/showth...threadid=42014
Latter Grandpa