First, click START (the round Windows system, lower left)
On the next screen/right side click CONTROL PANEL
Then SYSTEM MAINTENANCE
Then SYSTEM
That will show you how much RAM you have. If less than 2 Gig, get thee to a computer store and have them add whatever the computer will take. 3-4 Gig is nice.
But before even that, go to Symantec and get their Norton Anti-Virus program (if you don't have it already.)
Norton AntiVirus, 360, SystemWorks & Internet Security Software Suite - Symantec Store Products
If remember right, HP ships with Norton installed free for 90 days. If you have allowed it to expire, either download the next version or go buy it at the store. I advise the store if you are are already infected so as not to expose credit card info on a possibly-infected computer.
Next, go to
http://www.pctools.com/spyware-doctor/
and download/intstall SPYWARE DOCTOR. It will clean up all the adware that even Norton will miss. I recommend it highly.
You're looking at a couple hours clean up, but you probably will be fine.