windows 7 - 1 TB hdd and no space to create a partition for linux !

I have a brand new Acer aspire 5811 with core i5 processor and all that.

There is windows 7 Home Premium pre-installed on it. I want to install arch and setup a dual boot system.

EDIT: Looks like I have also another
issue. I have a dynamic disk. I really
don't know what it could be, but it
apparently means that I cannot use
Gparted (or any linux based tool) to
delete the recovery partition. Windows
7 disk management tool doesn't allow
me to delete it.

The problem is:

Windows shows 4 partitions

1. 14 GB UNKNOWN recovery partition


2. 100MB NTFS System Reserved partition for Windows 7


3. 448GB NTFS Windows 7 system partition


4. 468GB NTFS Data partition for windows 7

But GpartedLive cd and also arch setup show 5 partitions

1. 938Kb UNKOWN system reserved partition


2. 14 GB UNKNOWN recovery partition


3. 100MB NTFS System Reserved partition for Windows 7


4. 448GB NTFS Windows 7 system partition


5. 468GB unusable space

Because of this, I cannot create another primary partition.

Can any body guide me about how should I go for creating partition for installing arch ?

Note: I need to keep windows 7 working.

regards.