./vers 
If some fields are empty or look unusual you may have an old version.
Compare to the current minimal requirements in Documentation/Changes.
 
Linux millard.fxserver.com 2.4.20-30.9smp #1 SMP Wed Feb 4 20:36:46 EST 2004 i686 i686 i386 GNU/Linux
 
Gnu C                  gcc (GCC) 3.2.2 20030222 (Red Hat Linux 3.2.2-5) Copyright (C) 2002 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Gnu make               3.79.1
util-linux             2.11y
mount                  2.11y
modutils               2.4.22
e2fsprogs              1.32
pcmcia-cs              3.1.31
PPP                    2.4.1
isdn4k-utils           3.1pre4
Linux C Library        2.3.2
Dynamic linker (ldd)   2.3.2
Procps                 2.0.11
Net-tools              1.60
Kbd                    1.08
Sh-utils               4.5.3
Modules Loaded         ide-tape lp parport sg esm ppp_async ppp_generic slhc iptable_filter ip_tables tg3 ide-cd cdrom keybdev mousedev hid input usb-ohci usbcore ext3 jbd aacraid sd_mod scsi_mod