How Do I Clean Up Registry

My laptop and my desktop both take a very long time to boot. I think I've learned online that the best way to speed things up is to clean up the registry. I know it (both, actually) need this done. Can someone point me in the right direction so I don't accidentally crash one or both my systems? Thanks!

 

There are utilities to do this and may here swear by CCleaner - PC Optimization and Cleaning - Free Download. No matter which utitily you choose I would do a full system image of your systems to an external hard dirve. I would also run a full virus scan (in safe mode) and use a malware program such as Malwarebytes to rule out any rouge programs.
GR8 suggestion by Tijo, an easy way to test is do a clean boot - for XP http://support.microsoft.com/kb/310353
If none of this speeds up your machines a clean install of your OS or a factory reset may be needed.

 

I got a feeling startup entries might be the culprits rather than the registry.

 

Run ccleaner, imo do not use anything else for registry cleaning.
For startup entries, use ccleaner as well, untick the entries you may not need, can be re-enabled if you went over the top.

Check processes using Task Manager, look for those with high cpu\high memory use, carefully disabling some of them in Computer Management > Services.
Helpful references: the Windows Services info on Black Viper's Website

Do a backup\system restore point\disk image before venturing too deep. If all attempts at getting speed back fails, reinstall is the best bet. btw, am supposing you're not basically too low on memory.