Raid 10/VMware Host ?

I Have a client that has 2 vmware host with 4 500gb drives configured for Raid 10 (Dell PE T420 servers  PERC 710 Raid controller) VMware ESXI 5.1 essentials  not running on a USB or SD card ( One host is the AD, DNS, DHCP the other one is the backup/replicating AD, DNS,and is the file and printer server win 2008r2) Provisioned as Thin

The File server VM is running out of space

We want to replace the drives with 1 TB drives with a total of 4 tb and 2TB of space free to use.  Here are the drives we are looking at use to replace : http://www.neweggbusiness.com/product/product.aspx?item=9b-22-236-727WD Se WD1002F9YZ 1TB 7200 RPM 128MB Cache SATA 6.0Gb/s 3.5" Enterprise Hard Drive

The drives in the system are Dell 1 TB 7200 RPM 16MB cache Sata 6.0Gb.s 3.5 hot plug

Questions is what would be the best way to replace these drives can i replace them on the host and they will rebuild to the host configurations?

Or do I have to start fresh Install new drives configure the raid again and then re-provision the drives on the host?

If I have the first Dell Host server with the 4  500gb drives raid 10 ....can I put the bigger WD 1 TB drives in the 2nd server replacing the 4 500gb drives

Any and all suggestion are welcome