Can't remember which key it was - F I think? - but if you pressed it you went extra fast and you could out run the Yeti for a while but eventually you would hit something and that would be the end of it!
EDIT: A good reason for not having the pack is that the games were all made by different developers but were licensed to Microsoft for that Entertainment Pack. Also, most of the games weren't that good - there were just a few outstanding ones like Chips, SkiFree and the lasting classic that was FujiGolf!