The original TTD files are now checked with a MD5 sum to determine which version of the grf files is used and to warn about possible file corruptions. (Thanks to ledow for the original patch)
Please read the Readme for further information. There are some minor graphical glitches when you use the DOS files. E.g. the autorail button is a bit screwed up.
It has proper support for the euro sign and includes letters which are needed by the Latvian translation (and perhaps others), though the letter sprites are missing.