just wanted to ask if i convert avi files to DVD using Convertxtodvd,will it cause my avi file to lose its quality?
Is it better to just burn the avi file on cd/dvd without converting it to dvd?
You will lose some quaility almost regardless of what program(s) you use. Some programs more than others. It's also depending on file size. If you're authoring a full 700mb avi rip with ConvertXtoDVD, then you will see some quality loss, but usually never enough to make it unwatchable.
In my opinion, AVI2DVD or TheFilmMachine paired with HCEnc encoder, produces better results than ConvertXtoDVD. As far as burning the avi to CD/DVD player, you could do that, but note that it will not play on your DVD player.
With 700MB Xvid's ConvertX is all you will need, there isn't much (if anything) to be gained with the high class encoders. For the longer running time 1.4GB ones a high quality encoder like HCenc will make a slight difference. It's the nature of the beast... an Xvid's quality has already been compromised, there is only so much that can be done with it. They are meant to be an end product.