Wich RAM card should I get?

Hey guys.
The first time I bought a RAM card it didnt fit in to the slot,it was a DDR 512mb one.Then i changed it to a 1g DDR 2 RAM card
it fit into the slots,but when I turned on the computer the screen was black and the processor was beeping.I turned of the computer and tried all of the other slots and it still beeped after I turned the comp on.Can you guys give me a tip on wich one I should get or what I should do.
My computer settings are:AMD Antlon™ 64 processor 3500+,MMX 3d now,2.2GHZ
1022MB RAM

need more info: http://www.cpuid.com/softwares/cpu-z.html

download, run, post motherboard model #.

How the... I believe that DDR2 and DDR are not physically the same size, so how did you get it into the slot?

Well anyways, sounds like you got the socket 939 Athlon 64, it uses DDR RAM. You have to get DDR RAM, preferably DDR 400 with good timings.

look up the best RAM for your system and then order it from them or find a cheaper alternative of the same specs.

http://www.crucial.com/index.aspx

How the... I believe that DDR2 and DDR are not physically the same size, so how did you get it into the slot?

Well anyways, sounds like you got the socket 939 Athlon 64, it uses DDR RAM. You have to get DDR RAM, preferably DDR 400 with good timings.

they are different, you cant use a DDR on DDR2 slot, or a DDR2 on DDR slot.

How many beeps ur motherboard do?when its beep, most of the case are, or theres no memory ram, or no graphic card.

Well yeah the DDR one was bigger then the DDR 2 one,but the DDR one didnt fit and the DDR 2 one fit,but when i turn the computer back on its just a black screen and the processor starts beeping non stop

my mother board does 1 big beep and 2 quick smalls beeps after,lol
graphic card?like a video card, i have that i think...(omfg i suck with computers)
oh and actually the other ram cards were bigger then my DDR 2 ram card.
Maybe I should just give my RAM card to the store clerc and let him see wich one I need?Its a pain in the ass though couse its a 1 hour drive to the other freaking town to get to that computer store,and ive driven there 3 times already for the last 3 days.

If you've followed either Eos or my advice we would have known what you have and offered a suggestion.

Right now, with all the info you've given, one of two things I can think of:

-RAM mismatch (different voltage, timing, frequency)
-RAM not in the right slots (the ram slots are numbered, some motherboards require the first slot to be occupied at all times)

mainboard and motherboard are the same thing right?if so then my motherboard model is M2N-E

You need DDR2 800/667/533. Since you have 1GB already and is adding another, I suggest you buy TWO 1GB and get rid of your old one. OR get 2 x 2GB = 4GB. That way you avoid stability/compatibility issues with mix and matching RAM.

I have 2 512mb ones,can I just change one of those to one 1gb one,couse I dont really have alotta money xD

You could probably go 1 module and save up for an upgrade later but there is a catch. Some motherboard have a feature called Dual-Channel RAM, meaning if you have modules of the same type, size, and latency you can get faster speeds out of it.

If anything go for pairs of RAM modules. Newegg.com always has some for cheap at times. Kingston ValueRAM is inexpensive but has great performance I use it a lot for my customers.