What is the infected file name, where was it found e.g. (C:\windows\system32\infected-file-name.xxx) ?
Check the avast! Log Viewer (right click the avast 'a' icon), Warning section, this contains information on all avast detections.
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. Rather than delete and investigate as there is little you can do after deletion.
I tried a google search on the win32:small-jkw whilst it returns several hits they are all foreign language hits. You may be better trying a of these forums for it or a google search for win32:small, which would return a lot more hits.
Generally they are back doors (firewall bypass) into your system or droppers, downloading more malware.
What is your OS and Firewall ?
You might also want to scan with an anti-spyware tool. If you haven't already got this software (freeware), download, install, update and run it, preferably in safe mode.
1. If using winXP or Vista
SUPERantispyware On-Demand only in free version. Or
Spyware Terminator Resident scanner (if you use this don't install the toolbar or crawler or the anti-virus module). Or
a-Squared free On-Demand only with free version(if using win98/ME).
