> Sorry I rectify, My Graphics card is a Radeon 7700 [...] Hope this helps

Yes, it really does. First off, I'm astonished that MorphOS can display on your Radeon HD77xx at all (as you described in several comments), as I've never before read such thing and it really shouldn't, at least going by what's known regarding GPU support of MorphOS. Can anybody else confirm that MorphOS somehow/somewhat works (at least to some extent) on GCN1-based graphics cards?
So, if your GPU luckily isn't TeraScale2 but GCN1, which is 3D-supported by OS4 (with A-Eon drivers), then you're off the hook as you can keep this card for OS4 in the primary slot and just need to add to another slot a card 3D-supported by MorphOS and Linux, which would be R5xx-based, as has been mentioned numerous times in this thread.