Do you have any anti-virus scanning/'fixing' software installed on your machine ?
You are NOT going to receive any viruses in the act of downloading and installing LimeWire from the official LimeWire Download Site.
Obviously if you are using Task Manager than you are not exactly a total newbie !!!
When you look at
Processes in Task Manager, do you see any
svchost.exe examples of high CPU usage ?
What else - Other Applications - are you running at the same time as LimeWire ?
What other applications, if any, also exhibit deteriorated performance
without LW running ?
and a load more questions...