I've now added a new version of the algebra filter to cvs.../moodle/filter/. This uses the same database caching technique as the existing tex filter. I've tested it under both Linux and WinXP/EasyPHP. This filter requires that Perl be installed on the server, which of course is standard on Linux. For WinXP I used ActivePerl, downloaded from http://www.activestate.com/Products/ActivePerl/ - no customization is required.
For those who have not seen prior discussions here, the algebra filter allows mathematics to be entered in a calculator style syntax, simpler than that used by the TeX filter. On the other hand, it is more limited in the type of expressions that can be entered. However it should be adequate for courses at the secondary school level and lower level university courses.
PS. Perhaps you should move the texh filter out of the main cvs tree and into contrib. It is not fully functional without the hevea/imagen/CAML binaries, and may confuse users.