Can I add to existing RAM - or do I need to trash it

[sargan]

Memory Q on a Dell Dimesnion E521
This has 1 GB of RAM ... 2 x 512MB MEMORY DUAL CHANNEL 533MHZ DDR2

The Motherboard has 4 x memory slots .... can I add 2 x 1 GB memory modules ... to give overall 3GB ?

or does what is in the 'empty' 2 slots have to match what is in the currently used slots.

 

[o1die]

You can use the old ram. 3 gb is plenty for 32 bit windows. I would match the brand and speed if possible. Check craigslist for used dell ram if you can. I've seen 2gb for $20-25. Be sure you get desktop and not notebook ram.