|Disable autorun before you plug in anything your not sure of.|
In fact, disable autorun for everything and leave it disabled from then on out.
The first thing a virus may go after is to kill your antivirus engine preventing detection.
Anyway, I am no expert, but I have to agree. There are new and unknown viruses daily. If things are just too questionable for you, do a DOD level 3 wipe and start over.
It's allot of work and allot of down time. Less so if your doing full disk image backups maybe. In the end it may not take care of everything, like an infected BIOS, long term storage, or your USB stick.
If your going to live at all just get over it. Find out more about the infection and what it's capable of. Symantec, or your own antivirus provider's website is a good source of information.
Not everything flagged will have a name. Some things are just given a name placing them in a category as suspicious Trojan or whatever and may or may not pose a real threat. Some things are just false positives (contact the software manufacturer).
Booting from CD is a good idea. Also, you could just disconnect your hard drives internally while you work on the USB stick.
I am not sure what Shift-delete does. If that's just select all and delete though, its not enough. I would wipe it and reformat completely after your antivirus says its ok and you remove what benign things you recognize. You need to get at all the partitions clean and even the unallocated space. It's just a flash drive, not your hard drive, so why not.
Also, your antivirus may fail to detect everything post infection. I would run a root kit scanner like Norton Power Eraser. Keep in mind it is likely to flag more threats then are real. You could also run CCleaner or Barracuda. And then run your antivirus again. They can expose things that your antivirus might otherwise not pickup.
Or just destroy and throw the stick away. They don't cost that much. Is it worth the headache?