Yes, it's an old OS now, though it serves it's purpose as a web browsing machine with Chrome installed. My old works Dell Latitude D820 XP laptop I hadn't touched in years and was painfully slow when I booted it up. I realised why it hadn't been touched. I replaced the hard drive some time ago and at first it was quick, but soon started running slow. I'd also stripped it down, removed the old dry thermal past, applied new paste and that helped a little. That was probably two years ago.
I booted it back up having forgot just how slow it was, after using it for a few minutes I decided to try do something about it, here are the tools I used to turn the tortoise into a blazing fast hare!
Defraggler - my defrag tool of choice now days.
CCleaner - Does what it needs too.
Both of the above can be obtained here
Now what sort of IT type would I be if that's all I had done to improve the laptop's performance?
Go in to the System properties > Advanced > Performance options and choose Adjust for best performance.
Open My Computer, click your drives and choose properties and uncheck the Indexing option and Click Ok.
Open Services.msc and stop the Themes service and then disable it, do the same for the Indexing Service, Windows Search. Stop and Disable any services you don't need, if you're not sure about them research it first. If you're not using wireless do the same for the Wireless Zero Configuration, but remember you've disabled it and will need to enable it if you want to use Wireless again.
Delete anything in Start > All Programs > Startup that you don't need.
You can also use the MSCONFIG utility to disable other Startup items that are system side rather than user specific.
Down to the nitty gritty registry changes, copy the below and paste into a text file and rename it from .txt to .reg then right click it and choose merge. But please do backup your registry first, "Just in case".
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Session Manager\Memory Management]
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management]
NOTE: A few things to note about the registry changes above, the UDMA66 setting will only help a specific set of drives called ATA, not the newer SATA drives.
Hopefully you'll now have a much faster system you can re-purpose or hand down to the kids!