Thanks for your help. Here's the capacity info:
C DRIVE: 16.45 GB capacity, 3.3 GB free
D Drive: 17.66 GB capacity, 17.38 GB free
And here's what I eventually found on the Acer site:
The hard drive is partitioned into three partitions by design. If you look in My Computer you will see two of these partitions,
On older units they are listed as "Acer (C:)" and "Acerdata (D:)" [THIS IS MY 3620]
On newer units they are listed as just "(C:)" and "(D:)"
(C:) is where the operating system and all software is installed.
(D:) is for you to use as storage.
The (D:) drive protects your data if you ever have to reformat due to a virus or other corruption. The data in the (D:) will not be erased.
The third partition is not shown in My Computer. This partition has the files necessary for the Acer eRecovery to:
1. Reinstall the operating system, setting the system back to the way it was the day you purchased it.
2. Create copies of the factory installation CD's.
3. Create a snapshot of your current configuration, you can then use that configuration if you have to wipe out the operating system.
4. Reinstall just the drivers or applications that came preinstalled on the system.
If you prefer to remove all the partitioning and have the hard drive set up as one large partition, you are free to do this however Acer does not provide software for this purpose. You will need to use a third party formatting utility like Fdisk or Partition Magic to create, change or delete partitions. Partition Magic can be used to manipulate partitions in Windows without losing data. Again this is something that Acer does not provide or support; you will need to contact the manufacturer of Partition Magic for assistance on how-to questions using their software.
So from the above, it appears that I can remove that partition, I need to do a little more research on whether or not it's a good idea.