Type the names of the missing drivers (mssp232.dll and mssp3GE.dll) into a search engine. You will find that many people have this problem, i.e. you'll find these names cropping up in newsgroups and such. Chances are that you will also find a site where you can download these drivers. Download them into: ...\Program Files\Common Files\Microsoft Shared\Proof\. This is step no. 1. Step no. 2 is getting the driver mssp2_ge.lex. Grab it here: http://willow.cats.ohiou.edu/~lrc/germanware/proofing/.
Download it into the same folder (..Microsoft/Shared/Proof). Now, Word 2000 will be able to spellcheck German documents.