Ok instead of worrying about new parts why not speed up what you have.
Download Ccleaner- Download CCleaner 2.05.555 - filehippo.com
Tick every box in both the little tabs and run the cleaner.
Now, after that is done, go to the registry cleaner tab and run a registry clean. It will ask you to make a backup which you can if you want, i usually don't. Click fix all and then it will clean your registry.
Then download O&O Defrag Trial - Download O&O Defrag Professional Edition 10 Free Trial - Defragmentation tool for Win 2000/XP/Vista
Run a 'Stealth' defrag on all the drives you have (inside the program it has a help function if your stuck)
Finally disable everything that starts up from your computer but your anti - virus.
Start > Run > Msconfig > Startup Tab > Disable everything but your Anti-virus.
Also you may want to consider uninstalling Mcaffe - |MG| Mcafee UnInstaller 6.5
And instead of that get AVG Free, an excellent virus program. - Download AVG Free Edition 7.5.519 - filehippo.com
Hope this helps