I doubt it the recovery partition that's causing the problem.
Ideally you would keep the other HD (sdb) in place, and have grub on there - as you say it has been. This is better IMO as it helps preserve the integrity of sda
The CRUCIAL thing is boot order, and in the case of both being SATA drives you may actually have to change the order they are plugged in to the mobo. If sdb is a pata/ide drive it's ok, but it needs to be Master on the jumper.
Principle ideas here:
Partitioning/Install Guide - openSUSE Forums