Yes, you are better off leaving unallocated space for Linux installs - i.e. don't create a partition for it in advance.
Also, don't do the install "in" Windows (known as wubi) - do a"normal" install into the free space, and let it build a dualboot menu for you.
<Edit> If the machine is from the last few years (3-5) there shouldn't be any BIOS specific problems loading.
Last edited by syg00; 03-19-2010 at 07:15 PM.