Question:
my computer configuration
512RAM(DDR1)
AMD Sempron

Best Answer:
You can use a registry cleaner to clean up your computer and then make your computer faster,Why?the reason is that there may be some registry errors and remnant,corrupt files and temp files in your computer to cause “computer slow”.
Every time you install and uninstall software on your computer and surfing online you create junk in the computer registry.over time, the registry can grow to enormous proportions, especially if the various programs you’ve installed do not do a good job of deleting and/or updating it’s Registry entries.You need to scan and clean your computer with registry cleaner to make it fast.Good Registry Cleaner will improve your computer and Internet performance dramatically!
There are some comparison and review of TOP 5 registry cleaners.
http://speed-up-my-computer.com
You can download and scan your computer for free.