@GreenHawk84 - I think the vector code for mame2003 and mame2003-plus are pretty much identical now.

One thing that has changed is instead of a vector resolution multiplier of 1, 2, 3, etc. it will be the actual render resolution under the Quick Menu -> Options settings.

If one of the core resolutions match the native native resolution of your monitor it should like decent. If you can't match the resolution to the display exactly then shoot for something close. I find using an HD display (1920x1080) that 1440x1080 looks decent for both horizontal and vertical vector games.

Try a vector beam width of 1 or 1.2 (Quick Menu -> Options) and if it still doesn't look satisfactory try turning on bi-linear filtering under Settings -> Video.

Some of the options require a core restart, basically exit the game and restart it.