I want to upgrade my RAM for my Dell E521? Need help please.?

Question

I want to upgrade my RAM on my Dell Dimension E521 as it's only 1GB currently but I'm a complete newb at computers.
If someone could help me answer these following questions:

Should I get 1*4GB, 2*2GB, 4*1GB?

Which brand of RAM should I get? (I live in UK and I don't know which brand of RAM and what mhz works on my computer so if you can find out for me and tell me which one does, that would be great, like I said, I'm a complete newb).

Will the increase my computers current performance anyway? (I checked on the task manager, performance and it the free physical memory (mb) hovers around 0)

Here is my full specification for my computer.
http://support.dell.com/support/edocs/systems/dime521/en/SM_EN/specs.htm

Answer 1

Upgrading your memory will increase your computer's performance, make sure you get DDR2 DIMM memory, and make sure it's for the correct form factor (don't buy laptop RAM)



Here is the service manual for your computer:

http://support.dell.com/support/edocs/systems/dimE521/en/SM_EN/parts.htm#wp1043338

It will give you detailed instructions on how to install/uninstall your memory for that specific computer



Here is some information on memory in general (basic info): http://the-computer-wizard.tripod.com/Documents/Upgrading_Memory.pdf

Answer 2

make sure you can up the ram first

Answer 3

http://www.google.co.uk/products/catalog?q=ddr2+800mhz&hl=en&safe=off&rlz=1C1NIKB_enGB509GB509&psj=1&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.&bvm=bv.1355534169,d.ZG4&bpcl=40096503&biw=1920&bih=979&um=1&ie=UTF-8&cid=4967095498329571860&sa=X&ei=vaXlUN3_M-iU0QXUh4G4AQ&ved=0CKUBEPMCMAk