Done the whole procedure, still got major issues

Hi, I have a some problems with an XP laptop. About 2-3 years ago I noticed that everything was slowing down. It didn't happen at a particular time, it just kind of built up over a period of a couple of months. I went through a lot of procedures - defragging, registry tuning etc, with very little noticeable difference. I ended up buying a new computer and I mainly use that. Every now and then I start up the lap top and try to fix it butI can't find out what the problem is. Now I need to use the laptop again and I really want to fix this problem:

Startup times are L-O-N-G, anywhere from ten or fifteen minutes to half an hour or even longer. Lots and lots of activity on the hard drive, and very very slow at opening up windows and applications. I have followed your procedures in READ & RUN ME FIRST to the letter, the only exception being that I had just done a sweep with Spyboy S&D before I got onto your website so I didn't do it again. Logs are attached. I would really appreciate your help!

 

Here is the MGTools log.

 

This is indeed a major problem - I don't know what it is that's taking up so much memory. I've been through the processes and tried to eliminate all the ones I don't need. The only stuff I have running in the background is Norton Internet Security and the usual tray items. I tried to install Ad-Aware the other day and got a message saying there wasn't enough memory!
Can you tell me how I can find out what it is that's taking up so much memory? And why is it that I have to wait so long whenever I start up before I can do anything? I'm talking sometimes 20-30 mins!