Installing Lindows will over-write MBR with LILO. Probably only Lindows and Windows will be available as boot options first, but adding Mandrake manually is a pita. After installation, boot Lindows and edit the file /etc/lilo.conf. Then right click the file /sbin/jiffyboot and remove the executable permissions.
Now Mandrake will be bootable. Just ask me if you need more specific instructions, but first install Lindows. Btw, if you're a CNR member I recommend you get the latest Linspire 4.5 ISO instead (it's under My.Linspire -> My Products -> CD Downloads).
If you're not a CNR member I recommend you get the LindowsPlus package since it's only $20 (temoprary offer) and includes one year CNR! You can buy several and each of them will add another year to your subscription. Normally CNR is $49 a year so this is a very good offer.
You can find the offer here:
http://linspire.com/blowout.php
Btw, you know that you'll be able to get all the latest versions of Linspire as ISO's once they are released, as long as you subscribe to CNR...