if the serial is on the back he can borrow a disc of the same version and install it and download drivers from ibm website 
Not without ringing Microsoft and begging - IBM/Lenovo use preactivation, therefore all the keys on the COAs are invalidated at the MS clearing house 
To OP - tell your mate he is a silly arse for throwing that out
. He needs to ring Lenovo to buy a recovery disk. Or buy a retail copy of XP (if he can find one).
Are you sure??
My Thinkpad T43 'ate' it's hard disk recently, recovery partition and all!!

, and no recovery disks either!!

Bought a new, larger h/d, loaded a copy of XP pro from my desktop, entered the original T43's COA, and away we went. It validated OK, and all the 'windows genuine advantage' checks are all OK, and all updates have been added as they arrive??
Basically, the machine is now, 'as it was' minus the recovery partition. All that is different is the fact I get a different startup screen stating 'This disk is not certified by IBM' press F1 to reboot, or 'enter' to continue. If left alone, it then boots as normal. (assume the startup is because its looking for the recovery partition) , but it works OK!!
Try it, nothing to lose.
(there is a guy on flea-bay selling genuine recovery disk sets for certain model thinkpads, try your model no in the search box and see)
Hope this helps..
