in PRO/E, you would click on the dim, enter a , say -1.25,and the hole would move to the other side of center by 1.25.
in solidworks......... open the sketch, right click dimension,change to driven, move to approximate position, right click dim,change to driving, double click dimension, input new value, closesketch, rebuild
much simplier in Pro/E, IMHO. i've been trying to figureoutfor teh last 7 years why SW doesn't have this....
I don`t know why solidworks not provide negative dimension. But in solidworks, you can use reverse direction. Or if you have solidworks 2008, you can use instant 3D. Instant 3D provide "negative value"
Regards,
DD