Real Memory Usage

[Bill Matthews]

Hello,

I have a box running RHEL 3 with 2GB of RAM.  I am graphing memory
usage with MRTG.

The box consistant runs at 5% CPU, but 95% memory usage.  So something
is using a heck of a lot of RAM.  The box just has some basic services
on it (web server, mrtg, etc).  So I'm not sure what could be using
that much RAM.

Being new to Linux...how do I tell what processes are using how much memory?

Here's an output from vmstat 

vmstat 5 5
procs                      memory      swap          io     system         cpu
 r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy wa id
 0  0      0 291788 149368 1368452    0    0     2     3    2     3  2  1  0  7
 0  1      0 291876 149368 1368448    0    0     0   739  137   103  3  3  0 95
 0  1      0 292128 149368 1368452    0    0     0   370  164    50  1  0  1 98
 0  0      0 292344 149368 1368456    0    0     0   135  136   215  1  2  0 96
 0  0      0 291968 149368 1368456    0    0     0   112  312   204  2  1  0 98

So you can see it only has 300MB of memory free, meaning 1.7GB is
used.   The only commands I'm familiar with our ps -aef and top.

top shows %MEM but almost all processes are 0.0%. Some are 0.5 or 0.1.

Not sure where to look?

Thanks
BM