I would recommend looking for RAM at this site:
http://www.crucial.com/
It is a very good site which has been running successfully for a couple of years now. Use there system scanner to identify...

Have you checked that you actually only have 2Gb of RAM? May be worth checking. Also how many sticks of the RAM do you have?

What specifications has your computer got? (amount of RAM, CPU, PSu etc.)

With typing 'msconfig' into 'Run' , be sure to keep checked anything that says windows in the location, otherwise un-tick all the others, this can be found on the 'Start-up' tab.
To re-install your...

Your computer could recieve the wireless signal if you bought either; a PCI wireless expansion card, or a wireless USB stick. The latter option is the cheapest and most effective. Seeing as it...

Is your router wireless at all?
If so you could try and get a wireless connection just to see if the router is at fault. This problem seems to be linked to the modem & router hardware.
Also what...

Have you tried connecting via an ethernet (RJ45) cable?
Either find one that you used, or buy one (very cheap seeing as every one has gone wireless crazy) then connect one side to the router and the...

Did the modem come with an instalation CD?
Is it a plain modem that connects via a (Blue) USB cable? Or is it a Modem inbuilt into a router?

Try the long way:
Control Panel => Add Hardware => Follow all the instructions shown in the wizard.
If this doesn't help, come back to us.

How many programs have you installed onto your computer or how much of your HDD are you using up?
A large amount of usage = long wait, but it shouldn't really be that long, how long are we talking,...

Are you the administrator?
Also has the virus been totally wiped from ur machine?