Credit rolls are tricky no matter what the format- tape,
film, web. Serif fonts with fine lines can be quite
difficult to work with. I've done tons of credits and
there's always some hassle, but once you know what the
issues are you can do great credits in Vegas.

Here's what I'd do:

1) Carefully consider the font. Helvetica/Swiss, Bookman,
Impact and san-serif fonts work better than TimesRoman and
the other serif fonts (serifs are the fine 1 pixel lines
and curlies- these can fall apart as they cross scan lines,
which they must do if they roll)

2) Try applying motion blur to the credit roll. This will
mean rendering the credits in a separate project as you
probably don't want to moblur the whole project

3) Resampling may help

4) Remember that each compression type, output size and
frame rate will impact the look of the credits, so you may
have to adjust on a "per destination basis"

5) May favorite: Blow off the roll entirely! Fade in and
out of static credit pages- maybe even key the text over
other graphics or video scenes. This choice lets you forget
about the scan line headaches, makes it easier to time the
credit sequence, and makes the inevitable changes to the
credits easier to implement. Plus, you can use the finer-
lined fonts more easily.

Good luck-