Does anybody know of a plugin for windows that functions like doscript

Do Script offers a much requested feature for FileMaker Pro. Upon exiting a field, a script can be triggered to run. Commonly called event-based scripting.

Both Troi (www.troi.com) and Waves in Mothion (www.wmotion.com) offer Windows plugins for what you want.

There are three leading commercial plug-ins which provide script scheduling capabilities, two of which Steve hjas mentioned - the other being SCRIPTit from CNS. The direct links to pages detailing each of them are:

Troi Activator:

http://www.troi.com/software/activatorplugin.html

Comm-Unity Networking Systems:

http://scriptit.cnsplug-ins.com/

oAzium Events:

http://wmotion.com/events.html

Each of the above is notable for being cross-platform. There are various others (of which do-script is one) which are specific to one platform.

Needless to say, there are significant advantages in using an x-plat plug-in within an x-plat solution, since you can use most or all of the code on both platforms (rather than having to code all external calls twice and then code conditional statements which choose the appropriate code for the current platform).

However it's worth noting that each of the above plug-ins has its particular strengths, specialities and extended features so they are not direct substitutes for one another (although they all provide script triggering capabilities) so it would be well worth you investigating all three before making a decision.

I won't go into their features here, because you'll find abundant details and demo downloads at each of the links above if you're interested.