Yeah, recording software can affect the quality of the burn.
I suppose that adding a great amount of RAM to a fast computer system could cover most software differences. However, on most systems, the software buffer behaves differently according to system load, available ram, and the writer of the software.
On my system, Nero burns poorly with choppy video playback. DVDDecryptor does a very good job, and RecordNow gets even higher quality (with much more speed). I'm just comparing ISO writing there.
Oh, and I removed all VSO and VSO based (computer-killing Patton Couffin Driver #&#$!!!) software from my system because the recording method in use tended to jam up my set-top player.