Adding borders (making movie widescreen?)

[Doug21]

First of all i have downloaded a three part xvid.
The first part of this movie plays in a widescreen format (with borders at the top and bottom - in a letterbox format( think that is the right terminology - correct me if im wrong).
Anyway the second and third part both full the screen and the picture looks stretched (if that makes any sense.

what i need to know is there any way of correcting parts 2 and 3 so they play exactly like part 1 (in a letterbox format)or am i stuck with them the way they are??.

i use tmpgenc and virtualdub and would be gratefull of help.

ta in advance

[Doug21]

got it sorted - it was just me be stupid as usual doh

hate sunday hangovers - cheers to anyone who was going to reply