After change kernel from 2.4 to 2.6 (actually 2.6.2, but problem exists in
ealier 2.6 too) in System Monitor info
about memory & swap utilization is wrong
(https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=108034). I see that
it is used 0 bytes of
4K of memory and 0 bytes of 11K of swap (second values change sametimes).
I reported this bug in system-monitor section (Bug 129562), but after 
lecture of "The post-halloween document" v0.48 by Dave Jones I think this
is problem with LibGTop.

<QUOTA>
procps.
~~~~~~~
- The 2.6 /proc filesystems changed some statistics, which confuse
older versions of procps. Rik van Riel and Robert Love have been
maintaining a version of procps during the development of 2.6 which
tracks changes to /proc which you can find at 
http://tech9.net/rml/procps/
- Alternatively, the procps by Albert Cahalan now supports the altered
formats since v3.0.5  -- http://procps.sf.net/
- The /proc/meminfo format changed slightly which also broke gtop in
strange ways. Likely this also broke some of the KDE/GNOME panel applets.
</QUOTA>

So I report it here. Because I don't have 100% memory utilization I'm not
sure that it's the same that
http://bugzilla.gnome.org/show_bug.cgi?id=129721 . I have Athlon processor.