Acer :: Partitioning For Vista And XP

I'm just bought an Acer Aspire 6930G and here's how my partitions look now:

Now I want to divide the partition C: into 3 partitions as following:

1.Windows Vista (The Current One and must stay as it is now)

2.Windows XP (Want to install it and use it as my 2nd OS)

3.Accessories (Just Some Files)

I've already tried shrinking them but failed as there's already 4 partitions exist in my HD! So my questions is how can I create the partitions as the way I want it?

I Haven't made backup dvd's yet so the current windows musn't be harmed and New partition should allow me to install new windows (XP) and use it as my 2nd OS