You'll need a decent capture or video card. AIW, Hauppage and Canopus are the best ones. You'd have to check whether they can recognise Beta format though. Nero 6 is a good burner and has the mpeg2 codec converter (best for dvd), already bundled so can convert from avi (it's uncompressed and is the format you'd be aiming for when transfered to pc).
DVD's are usually single, but the double-sided are quite pricey. (film-makers use industry layered dvd's so can fit much more on).