what are you hoping to gain from the conversion to c#? sounds like
you're looking at some architecture changes that are out of scope for
the project - your better bang for the buck might be to focus on
centralizing the data access code which might take you a couple weeks
if it's a large app anyway. anyone that's going to use 'modules all
over the place' probably doesn't have a clean data access model. if
you start trying to rip out those modules, use singleton objects and
static variables for example, you're probably going to find yourself
wanting to re-architect the entire thing and find yourself with a big
mess on your hands and nothing working. start with the data access and
dig back into the conversion as a separate project - that's my advice
from your initial description.
that said, there are code converters -
www.csharpenerforvb.com,
www.vbconversions.com - those are ads that pop up with your question.
it's a slippery slope...