What is it about OSs that make them go slower over time?
Unnecessary processes, services, scheduled tasks and programs. Get CCleaner, swot up on what you have running and whether you need it on / enabled / autostart, and disable or uninstall.
I have 16 of 22 startup items disabled, 6 of 7 scheduled tasks disabled, and if necessary, I could make it 18 and 7 respectively, if I didn't want a personalised startup. The four 'necessary ones' are 3rd party keyboard, mouse, security and audio software.
Processes (not including this browser and the task manager) - 10.
Services - 39 Auto, 4 Auto(DS), 11 disabled, 124 manual (they start when a program requests them).
Vista 64 with boot up memory usage of about 1.1GB out of 6GB. SSD boot time of 22 seconds on a three year old system.
It's all about taking back your hardware from your software. Ok, so there might be superfetch (a good thing - not sure if it's worth it on XP), but it's going to be next to useless if you're maxing out your RAM on boot up due to 100 processes that all want to be on at startup.
I used to offer folk help with this, but so few folk believe that their setup is the problem. They think that chucking more RAM and HDD space at the problem is the answer. Or upgrading to the latest version of a one size fits all operating system. And the last thing you ever want to install are programs that 'speed up the system' (other than ones that delete or disable things). They just add to the load.