WIN 7 Professional /Mozilla freeze, very slow

I have a desktop with WIN 7 Prof. and Mozilla as browser, HD 500 Gigs, 1 Gig RAM, connection is wireless and excellent. It is extremely slow to start, Mozilla freezes; have tried everything suggested by Mozilla Help but no success; Flash Shockwave crashes almost every time it opens. Have run antivirus (Avast), MAMB, SAS, CCleaner, defragmented the hard drive and nothing seems to help. Also, reinstalled the OS (upgrade option) but nothing changed. The computer is eMachines T5224, originally meant for Vista and the motherboard is discontinued; I bought it from a certified MS tech who had overhauled it and installed WIN 7 Prof. Looked at the drivers and scans tell me there are Vista drivers available. I am not that savvy with computers and don't know what to do. It is extremely frustrating to try to use the pc.

Would appreciate any help or suggestions as I am notin a position to buy a new pc.

Efrosina

 

Simple solution. You need more RAM - preferably 4 GB.
Visit Crucial and do a scan. It will show the type of RAM needed, as well as how much is supported by the motherboard.

http://www.crucial.com/usa/en/systemscanner

 

Thank you very much for the prompt response!
Will do the scan and see what happens - I don't download movies or music, I mostly do e-mail, Skype and reading different newspapers.

Efrosina