My Computer and I: One Way Out

My Dell Studio XPS 8100 has served me well for years now. Sooner or later, however, problems will arise, often ones that are difficult to troubleshoot. That goes with any computer system, anyway.

I have no formal training in information technology, yet I try to troubleshoot computer problems myself. With that arises a somewhat crude scientific investigation, testing one component at a time until the issue is located and fixed. So, what is the problem this time?

The problem:
While playing World of Warcraft, the game would go through random cycles of lag spikes and catch-up, lasting up to minutes at a time, sometimes disconnecting completely. While surfing the Web, webpages would randomly take minutes to load, if at all, and refreshing would sometimes retrieve the webpage in full.