Run top, and then press the 'M' (capital) to sort by memory usage... You'll usually see something like :-
1579 squid 0 0 15388 15M 1376 S 0.0 5.8 6:38 squid
1675 root 0 0 6324 6324 1476 S 0.0 2.4 0:01 console
5689 www 0 0 4808 4808 4644 S 0.0 1.8 0:00 httpd
5680 www 0 0 4784 4784 4624 S 0.0 1.8 0:00 httpd
5681 www 0 0 4784 4784 4624 S 0.0 1.8 0:00 httpd
5682 www 0 0 4784 4784 4628 S 0.0 1.8 0:00 httpd
5683 www 0 0 4784 4784 4628 S 0.0 1.8 0:00 httpd
5684 www 0 0 4784 4784 4620 S 0.0 1.8 0:00 httpd
5685 www 0 0 4784 4784 4624 S 0.0 1.8 0:00 httpd
5686 www 0 0 4784 4784 4628 S 0.0 1.8 0:00 httpd
5687 www 0 0 4784 4784 4624 S 0.0 1.8 0:00 httpd
5688 www 0 0 4784 4784 4628 S 0.0 1.8 0:00 httpd
1246 root 0 0 4692 4692 4560 S 0.0 1.7 0:11 httpd
1673 dns 0 0 4544 4544 2140 S 0.0 1.7 0:00 named
1678 dns 0 0 4544 4544 2140 S 0.0 1.7 0:02 named
1679 dns 0 0 4544 4544 2140 S 0.0 1.7 0:19 named
1680 dns 0 0 4544 4544 2140 S 0.0 1.7 0:09 named
1681 dns 0 0 4544 4544 2140 S 0.0 1.7 0:01 named
1540 mysql 0 0 4308 4308 1644 S 0.0 1.6 0:00 mysqld
1581 mysql 0 0 4308 4308 1644 S 0.0 1.6 0:03 mysqld
1582 mysql 0 0 4308 4308 1644 S 0.0 1.6 0:00 mysqld
1610 mysql 0 0 4308 4308 1644 S 0.0 1.6 0:00 mysqld
5445 admin 0 0 2888 2888 2664 S 0.0 1.1 0:00 httpd-admin
5453 admin 0 0 2888 2888 2664 S 0.0 1.1 0:00 httpd-admin
1457 admin 0 0 2884 2884 2660 S 0.0 1.1 0:00 httpd-admin
1454 root 0 0 2752 2752 2596 S 0.0 1.0 0:09 httpd-admin
note that Squid has grabbed 15M of ram and apache has grabbed almost 5M per child process. (serves me right for serving media rich content with dynamic content enabled to an intranet

)
I have 256M and about 3M free ( ~99%) without using any swap at the moment.
BTW this is a pretty clean 5.5b9 install until about 8 minutes time

Craig F.