Should I upgrade my HP a805n?

Hello, I have an HP a805n desktop that I've had memory added to last year and a graphics card - a Radeon 9250 w/256MB. As far as the memory goes, I cannot remember how much my husband added, but under the System Properties, it says there is a total 1.49GB of RAM. My trouble is with playing the Sims 2 games. I have most of the Sims 2 and expansions installed, but playing is real choppy and slow. The only other games I have installed are a few of the Real Arcade games which do not take up much space. I've removed many programs that I do not use frequently and cleaned and defragged. I have Windows Live One Care and Spybot which are current subscriptions that I run several times weekly. The original specs for my system are listed here: [url] http://h10025.www1.hp.com/ewfrf/wc [...] 44&lang=en[/url]

I would greatly appreciate some advice as I'm going through another major knee surgery in 3 weeks and would like to be able to play Sims 2 to help pass the time once I'm out of the hospital and rehab. center.

Thanks in advance!
~Suzie

G-paw, you're correct that my husband just added RAM to the existing system. I'm going to try the clean install w/ full format since I haven't done that in a while. I'm also going to try your other suggestions. I really appreciate your help and also listing the exact products I'll need to upgrade! I forgot to mention in my 1st post that I do notice hearing my fan come on alot more than I used to. I've used compressed air to blow out the dust inside, but it still comes on frequently whether I'm using the computer or not. I may have my hubby replace the fan too at the same time, but wonder if you have any suggestions as to which one to get, or does it matter?

Thanx,
Suzie