My Computer's ability?

I just began learning about PC's five months ago.Without knowing anything,I spent $599 on a HP desktop.It is:Pentium 4 HT,3.00Ghz,(2 cpu's)Vista Basic.It froze up alot at first,so I Installed 2 GB RAM(pny ddr 5300 2x1)and got a graphics card:Nvidia 8500 gt.After the upgrade,my vista score is 4.2,previuosly a 3.0.My security is AVG(paid edition)and I have System Mechanics 7.Is there anything more that I can do to increase the performance,such as external hard drive,or upgrade to Vista Premium?or have I reached the limit for improvements and just stay with what I have for now?Thanks.

My Computer's ability?anti virus software

Your computer spec. is nice, I think you do not need to upgrade it for a while. But you can change your OS to Winxp if you want your computer to work with more smoothly since vista use a lot of pc resource.

My Computer's ability?aurora

its fine no need to upgrade to VISTA

stick with XP it will last your for many years now

if it start to run slow then just reinstall XP with the recovery disks you have, after you have backed up your data ;-)
click on start on vista in search or run bar type in

msconfig and enter look on startup item if u have all checked onn unchek them and save and restart , after u boot up it will say u have blocked some prog