How to extend your C drive (primary system) partition

Use a partitioning tool like GParted (included on the PartedMagic LivecCD).

http://partedmagic.com/

You might want to download the free version of the EASEUS Partition Master ( http://www.partition-tool.com/download.htm) and then follow either of these two guides:

How to extend system partition (extend c drive)
http://www.partition-tool.com/easeus-partition-manager/extend-system-partition.htm

How to extend NTFS system partition without rebooting computer?
http://www.partition-tool.com/easeus-partition-manager/extend-ntfs-system-partition-without-reboot.htm

Personally i would use GPARTED, its done wonders for me too.
And i would stay away from EASEUS, it cause me more problems than any good. But its an opinion and for me to say its only bad would be, well ..... bad.

WHY?  WHY do you want to resize?  It's REASONABLY safe, but it STILL HAS A RISK.  The SAFEST thing to do - and also pretty quick - is to manage the C: drive appropriately.  Most of my systems have 12-20 GB and ALL have 25% or more free space.  I spend MAYBE 30 minutes a year doing a little maintenance, but other than that, I don't worry about it.

WHAT is taking up the space?  If you need help cleaning up the drive and moving DATA off the C: drive where most administrators agree, it does not belong, see http://www.lwcomputing.com/tips/static/bootdrivesize.asp

Look on attached video. I used PartedMagic 4 version which is free and open sourced tool: www.partedmagic.com
Take backup of your system before running it. The resize is really easy and simple. Download exe file and double click on it. The video will start itself.
increase-system-partition.exe

Normally I would agree with leew on this, but as this seems to be a new installation, and the separate space of that array hasn't been assigned or used for anything else yet, I don't see a big issue if either there was something that went wrong during the resizing, or making C larger. Of course you could stay with the current size of C and just add another partition and drive letter for the unused space, Which you could then use for temporary storage or transaction files for example.

Also, one thing to add to the utilities mentioned above, All depends on what type of RAID controller is used. If the Controller's driver is recognized by the utility it won't be an issue, if on the other hand it isn't (most likely with soft- or fake-raid controllers, which many SATA controllers built into PC mainboards are), the utility will probably see two separate HD's. If that was the case, you'd have to remove the 2nd disk from the array, do your resizing, then use the RAID utility to add the removed disk back to the array. In such a situation you could use the G4U tool which is also on the PartedMagic CD to make an image of the original partition first so you can easily restore it and don't have to reinstall the OS from scratch if something doesn't work (you can also use bootit-ng for imaging which gary mentioned above).

One last tip, sometimes it's wise to leave a small, emphasis on small, amount of unallocated space between and after partitions.  This was standard practice in the old UNIX days.  Why?  Well if a minor disk crash/bad sectors rears it's ugly head, after you do your badtracking to set-aside the bad spot, you'll still have enough room to redo the partition and recover from backup.  Depends somewhat on your backup strategies

According to the screenshot, you already have Unallocated Space after C, so the hard part is done.  There are two tools which may not cost you any money that are no less safe for your situation than a utility like Acronis.  If this is a Dell, you can use their ExtPart utility to extend C (it may not care if the system is a Dell or not, DiskPart will not work on the system partition).  You can also use a Server 2008 DVD to extend it.  I have never used GParted, but I understand it should not be used on Server OS partitions - worth looking into.

Just remember to make sure you have a backup if you choose an option other than leew's.

An additional note r.e. Boot-It ==>  Since you already have the free space after C:, this is an extremely simple & quick operation -- it will take well under a minute (just a couple seconds to do the actual resize, and a bit longer to do the error checks before & after -- Boot-It will not do anything if there are any structural errors in the partition ... that's one reason it's such a rock-solid utility).

The only issue is that Boot-It won't work if the RAID isn't enumerated at the BIOS level (i.e. a hardware controller chip).    But you'll also know that when you boot to the Boot-It screen ... if it shows two identical disks 40GB disks instead of a single one (the RAID array) then you'll know it isn't "seeing" the RAID correctly.

But as long as it sees the RAID, it's a rock-solid utility that will do what you want in just a few seconds.

Just remember that "rock-solid" is not a guarantee that nothing can go wrong.  Regardless of the method you choose, have a backup first.  There is no risk-free option for resizing system partitions.

Ok Great guys, I think I have enough information now. I think I will use Boot it first.