If some fields are empty or look unusual you may have an old version.
Compare to the current minimal requirements in Documentation/Changes.
 
Linux asterope0 2.6.20-xen-r6-xen0-smp #4 SMP Wed Dec 5 14:05:46 CET 2007 x86_64 AMD Athlon(tm) 64 X2 Dual Core Processor 4200+ AuthenticAMD GNU/Linux
 
Gnu C                  4.1.2
Gnu make               3.81
binutils               Binutils
util-linux             2.12r
mount                  2.12r
module-init-tools      3.4
e2fsprogs              1.40.3
reiserfsprogs          3.6.19
xfsprogs               2.9.4
Linux C Library        2.6.1
Dynamic linker (ldd)   2.6.1
Procps                 3.2.7
Net-tools              1.60
Kbd                    1.13
Sh-utils               6.9
udev                   115
Modules Loaded         af_packet raid456 xor raid1 8021q bridge llc capability commoncap thermal fan button ohci1394 ieee1394 k8temp usb_storage i2c_nforce2 forcedeth sg