[CentOS] Lost my win dual boot

Finally got my install working, Centos didn't recognise my m/board NIC 
so I had to install another NIC. Now, I've lost the windows install. I 
need it for my Walkman and Palm. Never, ever got any distro to see the 
Tunsgsten E. I can see the Win in Grub but it says there's a file 
missing, insert system disk. Where have I seen that before?
Anyway, how do I get into Grub and what do I need to add to make win 
bootable? Win is on sda2 amd Centos is on sda3 + 5. In the grub folder 
all it says in the system map is  (hd0)     /dev/sda.
Nothing else.
Ta.

Steve.