Heavy Memory Usage

On one of my computers, I am using XP Professional SP3 with 2 GB of memory and Pentium 4 2.8GHz processor speed. AVG is the anti-virus software.

For the last month of so, I have frequently seen AVG popping up telling me that my memory usage is heavy.. 500 MG, even though I was just using Windows Internet Explorer and with 2 tabs opened. AVG recommends shutting down I/E and re-open.

For example, while I am writing this thread, I have 3 I/E tabs opened...
Memory usages are 89,944K, 353,778K, and 305,508K.

Can someone explain to me what was going on...

Is this computer heading towards the garbage pile soon for for a open heart and neuro surgery ?

By the way, how to edit my Signature ?

Can't help with your Memory problem but to Edit your Signature click on User CP at the top then under Settings and Options click on Edit Signature.