Hello all i am new to the forum and just installed avast and i LOVE it had norton before but prefer this better.My ? is after u do a boot scan is it always better to have every thing deleted or quarantined.Also if u do a regular scan should u also delete what it finds and how do you know what to quarantine and what not.
Deletion isn’t really a good first option (you have none left), ‘first do no harm’ don’t delete, send virus to the chest and investigate.
There is no rush to delete anything from the chest, a protected area where it can do no harm. Anything that you send to the chest you should leave there for a few weeks. If after that time you have suffered no adverse effects from moving these to the chest, scan them again (inside the chest) and if they are still detected as viruses, delete them.
Norton can be a pig to remove all remnants and can be an issue with other security software you install later. A link worth looking at, which is a program removal tool that can remove the remnants of a number of different Norton Programs:
Removing your Norton program using SymNRT
As a new Avast! user myself, I was told to quarantine all infections. If you have a system file infected, you certainly don’t want to delete or you’ll have computer problems. I was also told to let an infected file soak for a few weeks in quarantine and then retest it. If it’s no longer infected you can restore it. Sorry, as I was typing DavidR entered pretty much almost the same answer. 
Wow, have I found someone that types slower than I do ;D