High MEM Usage??

[Sumith Ail]

Hello,   We have just received our server which is a Dual PIII with 512 MB RAM , RH Linux 6.2 Box. I have installed qmail on this with tcpserver, Now the meminfo shows cat /proc/meminfo           total:    used:    free:  shared: buffers:  cached: Mem:  529530880 364380160 165150720 72847360 300982272 24657920 Swap: 1048551424        0 1048551424 MemTotal:    517120 kB MemFree:     161280 kB MemShared:    71140 kB Buffers:     293928 kB Cached:       24080 kB BigTotal:         0 kB BigFree:          0 kB SwapTotal:  1023976 kB SwapFree:   1023976 kB                    There is hardly anybody using this server...please let me know how can I find out which process is using so much of memory.   Kind Regards Sumith