Personally, I do believe Vista's way of managing system resources differs a lot from XP, which could be a problem why it's being slow. Although, HP has a great tendency to install bloatware. If you have anything Norton or McAffee, please uninstall.
Get Avast Home Edition. Other than being free, it's much more effective.
If you can, you could grab a copy of Vista Retail, and inplement your own product key, and it'll get rid of all bloatware that it has. Also, afterwards, you'll need to run CCleaner (Download) and clean anything missing or remaining.
Also, since you have a gig, you could increase performance by unselecting unwanted applications from the startup tab in msconfig. Also, you could do a bit of research on Google on how to speed up Vista.
Originally Posted by Juice
Solution: Downgrade to xp, or get 4 gigs of ram.
What is it with you and such unhelpful answers?