Why is my MPEG too big?

[Mac Everyman]

I'm converting a 110 minute VHS video to DVD, but I simply cannot get it to fit on one disc. Details:

-- VHS captured to .AVI file with HuffyUV codex (no problem here)

-- .AVI converted to MPEG using TMPGEnc: I set the bitrate rather low (4150) and set the audio on "joint-stereo" (I *think* this should produce a mono track and thereby save some space -- am I wrong?) and it produces a 3.8 GB file....which, I should think, ought to fit just fine.

-- I then convert to MPEG to VOB files using MyVideo. Yeah, I know, not a swell program, but I only use it for conversion to VOBs. If I burn direct using this program, I get drink coasters. Anyway, this produces a collection of files that totals about 4.68 GB.

-- I then try to burn using Nero, but it rejects the project, saying the medium is too small for all those files.

I've successfully burned smaller files to DVD using the above method, so I know it can be done. But I'm baffled as to why I can't get an under-two-hour video onto a disc, particularly as I keep ratcheting down the bitrate. I suppose I could go lower, but wont I start compromising video quality?

[bugster]

Audio. I don't know anything about MyVideo but I would guess that it is converting the audio to PCM (uncompressed) when making the vobs. See if there is a setting that will allow mp2 audio (not standard for NTSC), or use a different authoring program that will allow this such as Ulead DVD WS os SPruce Up.