Gotta agree with Keista's son... although I wouldn't have used that exact language...
Total Physical Memory 256.00 MB = not nearly enough for most modern expectations.
Depending on which physical computer you have, it may be possible to double your RAM without putting too many $$ into it... depends on exactly "how old" the old machine is. (Tech explanation... the version of the Intel chip or equivalent determines how much RAM can be accessed, along with a million other things - lots of computers in the old days had a chip that would handle 512 mb RAM but shipped with 256 mb Ram - the extra memory was an "option" - and RAM at that point was expensive)
Just for comparison, the machine I'm on right this minute is my newest one... at it has 4 GB RAM... 1024 MB = 1 GB ... so my machine has something like 16x the memory of yours... and MINE runs out of memory sometimes. This one is a laptop with limited room... desktops are coming now with 8GB+ of RAM.
In reality, the only reason RAM becomes a problem is:
1) if you're doing a lot of stuff with graphics - because graphics are majorly RAM intensive, or
2) if you're doing a lot of stuff on the internet - because the internet is overloaded with extraneous stuff of all sorts.
If RAM is too low, system spends a lot of time "swapping" stuff from RAM to hard-drive and back - and not enough time doing "real work". There are checks built into the system, and when things take too long, the computer tries to take corrective action.
Hope that makes a TINY bit of sense.
Glossary:
GB = gigabytes = 1000 MB
MB = megabytes = 1000 KB
KB = kilobytes = 1000 bytes.
A bite can be used for lots of things, and what it can represent depends on how big it is. For many many years, a easy child "byte" was 8 "bits", and for comparison, represented one character (numbers are a whole different logic, as are machine instructions). Now, a "byte" can be 8, 16, 32, or 64 bits.