I am currently participating in my company sponsored 401k, my wife is a teacher and has a403b plan. Are we eligible to open Roth IRA's in addition to our other retirement accounts?

Yes, you are, if your adjusted gross income doesnt' exceed the IRS' limits. The limit is $160,000 if you file a joint return or $10,000 (yes, that's 10K, not $100,000) if you file separately.

There are no restrictions on eligibility conditioned on your participation in another retirement plan.

Hope this helps.