Hi everyone im new to this website, sorry if im asking newbie questions but this is a important sistuation, would really appreciate some advice.

My computer has 512mb ram wen purchased... since then its been reformatted twice.

The RAM on the computer is now 256 after 2 reformatts........... i go into system information and it says total physical memory 256mb RAM. SO i go to help and support and it says the same thing there, that it is 256mb RAM.

So i open up the comp to see if this is right but my RAM hardware is actually 512mb (thats what it says on the stick)
Now here what makes matters worse, wen i load computer up the BIOS says it is '512mb OK' and i did a hardware survey with steam and they said that it is 511mb of RAM.
WHat is my RAM, is it 512mb or 256mb? Is it rip off ram, or is there an error in windows? im really stuck sum1 plz plz help me i wud really appreciate it, thanks......

zebz