How to speed up my computer's Performance?

Hello, I would like to speed up my computer. after 2 years, my computer started getting down on me, and games i played when i first bought it now have a really bad fps rate.

i have:

-Checked for viruses

-Cleaned my disk (disk cleaner)

-Defragmented

and for games i tried game booster but i see no difference. Using Windows update i have my computer seemingly up to date.

My system:

Windows Vista home premium

AMD Phenom(tm) 9500 Quad-Core processor 2.20 GHz

3gb Ram

32-bit operating system

And games like dragon age 2 have a really bad fps rate. and Dragon age 2 says my computer has to be at least rated 4.5, with a recommended rating of 5.0, and my computer is 5.2

is there anything i should download or buy? If so can you tell me what and how/where to download/buy it?How to speed up my computer's Performance?
If you want to buy stuff:

Buy a new hardrive 7200rpm is fast enough install windows 7 on it (64-bit), throw your files from your old comp to your new.

Buy 4gb of ddr3 (max whatever your mobo supports), install them.

If you have onboard graphics and no pci slot then you'll need a new motherboard (I wouldn't bother then just upgrade the ram, hard drive and OS).

If you have a pci slot buy as new graphics card (whatever your board supports) Any card with 768mb to 1 gb of gddr5 ram should run dragon age II at a nice frame rate.

The card with the ram, OS, and hard drive will probably cost $250-$350. That will speed up your computer and increase you're fps. If you just upgrade the ram and hard drive with the OS it will make it a lot faster and cost $200-$250, but won't help much with games. (My prices are probably a little high)
Do a "check disk" on your system.

Check your start up programs. Many programs are started when you turn on your computer. These files occupy your important Memory space. Deleting unwanted programs will increase your performance tremendously.

Check that your C drive is not getting full. Having not enough space for the temporary files will slow down your computer also.

This should increase your performance with a low cost.How to speed up my computer's Performance?
upgrade to windows 7, prefably the 64 bit version, because the 32 bit will not allow you to expand your ram, and get a dedicated graphics card if you dont have one, and if you have a bad one, get a good one, that will make your games run much better.
windows registry, if your registry is crrupt, it will brings many problems. you can use a repair tool called registry cleaner to fix the errors on your computer and speed up computer. visit the link below

http://www.okpckit.comHow to speed up my computer's Performance?
your problem is windows vista no matter what you do it will be slow.