Vista - Disc Partitioning Problem with new Dell XPS Laptop

I have just bought a Dell XPS and want to mult-boot with Linux. I have
already build a similar system with my desktop although this machine is very
pre-Vista!

The PC has a 500GB (465.76) drive.

The partitioning structure is:
EISA Configuration 125MB (any one know what this is for?)
Recovery (D) 10GB
OS (C) 235.85GB
Unallocated 219.78GB

I am very disappointed that Dell have sacrificed three primaries for a
single OS!

Disc Manager wont allow me the shrink the C: drive any smaller despite only
having a few GB of programs on it. I would like to know why this
restriction applies and if I will cause problems if I try to shrink it with
a third party tools bearing in mind that Partition Magic apparently has a
problem with drives over 400GB.

Thanks in advance.

There are some important limitations to the Vista partitioning tools that you should keep in mind: you can only shrink and expand NTFS or RAW (unformatted) partitions; when you shrink, there are some unmovable files such as page files or shadow copy storage areas that inhibit the amount of shrinkage allowed; you cannot extend a partition into unallocated space to the left (lower disk addresses) of the partition to be added to; you cannot move around unallocated space; if you have too many bad clusters on the disk, then you cannot shrink a partition on it.

Boot-It NG is a shareware partition management utility that can be used to manage the shrinking and extending of partitions better than Vista's built-in tool. It has an old DOS style interface, but it works well. You can get it here:
Boot Manager, Partition Manager, and Drive Image Utility - BootIt Next Generation
I downloaded the free trial version and burned it to a CD with the included program MakeDisk.exe in order to be able to move some unallocated space immediately behind one of my four partitions that I wanted to extend. I just booted from the CD, clicked on the menu choice for "Partition Work", and then used the "partition slide" concept to move the unallocated space. The TerabyteUnlimited site has a good deal of documentation, tutorials, answers to FAQs, videos, etc. for how to use the program:
TeraByte Unlimited :: Support :: BootIt Next Generation

In addition to lee's post the D: partition and the EISA partition relate to the Dell Recovery system and not vista If you create recovery DVD's you should be able to reclaim that space