First going to

http://crucial.com/

Put in the details about your PC to find out whether or not you have more slots to put any RAM in.If it says you only have 2 slots then you will have to replace the existing RAM with 2 of the sizes you want to make your total.

Second, If you add one stick of 512 to your original 512, then yes you will have 1 gig.If your 512 is 2 256's i think it will only read the 256's. I heard somewhere that you have to add RAM in doubles.

hope this helps.

wait so like i can only buy 512 mb stick cards

Gigasearch may be right. I'm not sure that all PC's are like that but in many models all the memory modules have to be the same. I have some old P1's and some 486's that are not like that.

Anyway, it sounds like you're not exactly looking to splurge anyway and that you're not running particularly high-end apps. So, just open your box and see what you've got. If it's one 512mb chip then get another. If it's 2x 256mb then you can go on a spree and buy 2 big chips of your liking. Just take it out ant take it to the store wrapped in a static-proof bag and ask the guy for help.

You can help the environment and yourself by selling the old chips on ebay.

You can buy any size you want you just want to have the right version. I'd try getting double 512's and putting them in. That is if you have 4 slots. If you don't I'd just switch out the 256's.

Crucial reads your slots incorrectly, which should raise a screaming red flag by itself. And no matter what the results, even with up to 2GB already installed you'll get 'upgrade' options, so treat it like the scam that it is.

Download and run cpuz to see exactly what you already have in hand to work with, as knowing that is always THE place to start. If you don't know how to interpret what it says, either post back, or upload and link to an image of the results.

Here's a preview of what to expect: http://tinyurl.com/3rw873

I never knew it did, since when i put in my model and all that stuff it told the right amount.