Expand RAID 5 array on Dell Perc 6/i

Hello,
   I have a Dell r710 with the Perc 6/i controller.  I currently have a RAID 0 with one drive for the operating system and a RAID 5 with three drives for data.  They are 36 GB drives.  This was originally supposed to be an IT utility system for lab testing but has since become a semi-production system.  We run Hyper-V on it with some already configured VMs.  Well, we want to increase the drive space used in the quickest manner possible.  We bought some new drives for the data array and now I need to find the best way to move to the new drives.  Would it be possible to replace one 36 drive at a time, allow the array to rebuild to each drive before moving on to the next one, and then expanding the logical drive to use the remaining space on the larger drives?  Also, once that is done, can I then add additional drives to the array (we also have additional drive slots open we would like to use.  

My goal is to do this without any downtime for my VMs.  Not that they couldn't be down overnight, but rather the time it would take to copy them off and then back.