If you follow the advice given in that article, you should be able to put some life back into your laptop. Make a back-up first, and if things go awry then you can go back to where you started. I have done loads of reg cleans, and never had a problem, but back-up anyway.
Other things that won't do your PC any favours is running it with out adequate anti-virus, spyware, ad-ware programs. You don't have to pay, there are free ones that will do the job.
I use AVG 8.0 for virus, Ad-aware for ad-ware, and AVG of spyware. Also, you need a firewall.
A good way to avoid virus' is just to be careful what you use on the internet, the dodgier the content, generally speaking, the more likely you are to pick up nastys. P2P file sharing is great if you want a virus too.