Good morning Kiti
You are very welcome on the help. But please keep one thing in mind just like my last post if you do decide to move up to W7 64 bit make sure that all your software programs and all your hardware will work on W7 64 bit the MoBo and CPU etc are ready so don't worry about those. Just in case you don't know this the W7 that you are buying and downloading will be an ISO format if you don't have a ISO burner program just download the free ISO burner in the previous post. Plus if you move to W7 64 bit don't forget you will need to download 64 bit drivers when you move up.
If you are going to buy a new PS in my opinion you should get one from a well know company like this one
http://www.newegg.com/Product/Product.aspx?Item=N82E16817153023 it is $40.00 plus $5.00shipping plus it has a $10.00 rebate. I have used this same PS dozens of times. Good PS manufacture are "Thermaltake" Enwin, Enlight, Antec but one of the best value for dollars spent is the one in the link in this paragraph.
If you need anything else please come back and let us know, Mike