Memory problems

I'm not sure if this is the correct forum to ask this question, but here it
is:
Pg version: 7.2.1
OS - RedHat 7.2
ODBC - 7.2.1 Dual Processor
Memory - 512mg

I have a VB   app I created that will display a Crystal report within its
ActiveX control.  The Crystal report will call an ODBC DSN on the user
desktop that will populate the report.  After the data is returned, and the
connection status is IDLE, the memory usage for the connection according to
Top is 24.5% of memory usage.  Does this sound right?  Nothing is happening
during the idle state, so why would the memory usuage be so high?
Here's a copy of the running process with a user name of Postgres.  Note
that the mcom_users are all connected via  ODBC and the cjoarers are JDBC.
TIA
-patrick

48 processes: 47 sleeping, 1 running, 0 zombie, 0 stopped
CPU0 states:  0.0% user,  0.0% system,  0.0% nice, 100.0% idle
CPU1 states:  0.0% user,  0.2% system,  0.0% nice, 99.3% idle
Mem:   512924K av,  506488K used,    6436K free,  123460K shrd,    4736K
buff
Swap: 1048536K av,   60400K used,  988136K free                  294188K
cached

  PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME COMMAND
 5159 postgres   9   0  122M 122M  121M S     0.0 24.5   1:31 postgres:
mcom_user mdc_oz someIP_1idle
 5498 postgres   9   0 97728  95M 96536 S     0.0 19.0   0:03 postgres:
mcom_user mdc_oz someIP_2 idle
 5113 postgres   9   0 84668  82M 83492 S     0.0 16.4   1:08 postgres:
mcom_user mdc_oz someIP_3 idle
 5608 postgres   9   0 84656  82M 83532 S     0.0 16.4   0:05 postgres:
mcom_user mdc_oz someIP_4 idle
 5685 postgres   9   0 15864  15M 14928 S     0.0  3.0   0:00 postgres:
cjoarder mdc_oz someIP_5 idle
 5311 postgres   9   0 13748  13M 12932 S     0.0  2.6   0:00 postgres:
cjoarder mdc_oz someIP_6 idle
30127 postgres   9   0  1552 1180  1180 S     0.0  0.2   0:00 postgres:
cjoarder mdc_oz someIP_7 idle
13251 postgres   9   0   524  240   240 S     0.0  0.0   0:00 postgres:
stats collector process
30129 postgres   9   0   956  204   204 S     0.0  0.0   0:00 postgres:
cjoarder mdc_oz someIP_8 idle
13248 postgres   8   0   464  200   168 S     0.0  0.0   0:02
/usr/bin/postmaster
30128 postgres   9   0   948  196   196 S     0.0  0.0   0:00 postgres:
cjoarder mdc_oz someIP_9 idle
13250 postgres   9   0   484   72    48 S     0.0  0.0   0:00 postgres:
stats buffer process