|Quickest and most cost effective way I can think of is too..|
Convert and Back up all of your data files if possible to a text format... and what I mean by that is not changing the Font to Text; but exporting the files to an binary text format. ASCII
That will filter out any worms or Trojans that is attached to you data. inshort backing up all your keystoke work.
Then peruse over the files using a a dos editor looking for machine code.
Deleting any if you find it...
Next step would be to have another PC that is not effected by the virus or trojan... set up that PC to recieve Emails in ASCII Format only.
Then Send you Back ups to that computer via email...
If the virus trys to move with the data it will be frozen in a ASCII Format... which you will be able to quickly identify as machine code when perusing over the data the second time...
Then Moving the Data to an unaffected PC exporting the information back into the appropriate software packages.
"The Export option" should be found in the file menu based on your software being used to record your business activities.
"New unaffected PC" can be a computer that has been removed from the network that has had fresh install of all your programs and operating systems. "After reformatting the drive"
Hope that helps