Hello there and welcome to BleepingComputer.
There are no results on Google for those two files that AVG is listing as infected, but since it is better to be safe than sorry, I think it would be better to have them scanned by several more antiviruses, using a service called "Jotti".
Please visit the online Jotti Virus Scanner
Click on Browse
Then navigate to the bis612.exe
Click on the Open
The scanner will check the file with various antivirus companies.
Results will then be displayed which will tell you if any other companies have found the file to be infected. If you are unsure about whether they agree or not, or would like a second opinion, copy and paste the report into this thread and we will take a look at it for you.Repeat this processs with the other file.
With regards to your question about AVG or Nod32, I would personally go for Nod32 because I know of many people who think it is an excellent program, but AVG still ranks quite highly on the list; I used it in the past and had no problems with it. Obviously, it is not a good idea to run more than one antivirus at the same time. The reason for this is that if both products have their automatic (Real-Time) protection switched on, then those products which do not encrypt the virus strings within them can cause other antivirus products to create "false alarms". It can also lead to a clash as both products fight for access to files which are opened again this is the resident/automatic protection.
In general terms, the two programs may conflict and cause false alarms - when the antivirus software tells you that your PC has a virus when it actually doesn't. Also it can cause system performance problems; your system may lock up due to both software products attempting to access the same file at the same time.
Therefore, choose the one you prefer and keep it installed - the choice is entirely up to you - before removing the other one from your computer via Add or Remove Programs
in the Control Panel.