If you have two or more faces that are facing in a very similar direction, you can also right-click on one of them that looks ok, choose Texture > Projected, the sample that face (Paint Tool + Alt) and paint onto all the other faces. This will line all the textures up automatically, so you do not need to adjust each one.

Well, if it works only without hardware acceleration, it means that your video card is not fully OpenGL compliant. This also means that it will not "share the burden" of displaying the model with the processor so when you get to the limits of the processor, you will experience problems with bigger models sooner.

All in all - your SU performance may decrease. Best would be to upgrade to a better card (well, sooner or later). Have a look at the Apple OpenGL Chart for a comparison.

Otherwise I would recommend to upgrade your SU version to 7, too - although the Hardware requirements may even be a bit higher (especially OpenGL version - I think SU 6 needs 1.4 while SU 7 needs 1.5)