well, here the steps you have to take (no reboot is necessary):
first we have to make our kernel understand MPPE, for that you can pretty much follow this document:

http://pptpclient.sourceforge.net/howto-debian-dkms.phtml

In step c though you should only add the first entry into /etc/apt/sources, since dell has changed the url to the repository for Etch already and removed the old stuff for Sarge. So still we need fis this, so do that:

• apt-get install modutils
• wget "http://linux.dell.com/dkms/debian/dkms_2.0.16.1-1_all.deb"
  ( if Dell ever removes the file, I will attach it here to this article )
  
• dpkg -i dkms_2.0.16.1-1_all.deb
• rm -rf dkms_2.0.16.1-1_all.deb

Right after you have done that, you can carry on with step d and follow the document to the end and you will have MPPE in your kernel!


So now you can install the PPTP client and have fun with it, to achieve that, just follow this document: http://pptpclient.sourceforge.net/howto-debian.phtml#install