Here is some more information straight from Bart's website as well:
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Q: In what way is BartPE limited compared to a normal Windows XP installation?
A: BartPE has these limitations:
-To reduce its size, only a subset of the available Win32 APIs is included. Included are I/O (disk and network) and core Win32 APIs.
-Distributed File System (DFS) name resolution is not supported.
-The drive letters assigned during BartPE are not saved to any registry that persists when you reboot. The drive letter assignment when you create partitions is in the order of creation, but the drive letter assignments when you reboot will be in the default order.
-BartPE requires a VGA-compatible device and uses a screen resolution of 800 x 600 pixels. If BartPE cannot detect video settings, the default screen resolution is 640 x 480 pixels.
-BartPE is too large to fit on a floppy disk.
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Q: Does PE Builder remove the 24 hour time limit?
A: Older versions of PE Builder do not remove the 24 hour time limit.
Versions 3.0.33 and higher do remove the 24 hour time limit!
Q: Does PE Builder remove the "can only start 6 processes" limit?
A: Older versions of PE Builder do not remove the user resources limit.
Versions 3.0.33 and higher do remove the user resources limit!
QUOTE
When using BartPE you should know that:
It is legal to make a "backup copy" of ANY files from your original Windows XP/2003 media to another media.
It is legal to add any other files you wish to the backup media.
It is not legal to use a BartPE CD and an installed Windows XP/2003 both at the same time under the same Windows XP/2003 EULA.
It is not legal to change any binary files in the process according to the Windows XP/2003 EULA. This makes "winlogon" and "bootscreen" hacks illegal.
A BartPE image is (and I quote) "not a properly licensed WinPE". This means that if you want to have a licensed WinPE, you cannot use BartPE. However, you can use a BartPE image under the license of the Windows XP/2003 EULA that came with the BartPE XP/2003 source media.
Thus, I was thinking back to when there was a time and process limit, etc. :-\