Anyone Have Explorer Problems Working with Large Number of Large Files?

I have been working with home movies and saving them off to a Western
Digital 80 GB and 200 GB USB 2.0 external hard drive. I used Windows XP Disk
Management to create a NTFS partition for both of these drives, since they
were originally FAT32. My computer has a 2.53 gigahertz Intel Pentium 4
processor and 512 MB of RAM.

Most files are .5 to 1 GB in size. I created a folder and tried to move
approximately 50 files into it on the same drive using Windows Explorer. I
kept getting an error that some of the files were being used by another
program, even though I did everything to confirm that they were not.

I have also tried other operations, such as selecting a large number of
files, right clicking and selecting properties. This results in Explorer
become very slow/performing with a delay and either the results don't come
back or they take a very long time. When they do not come back, then
everything is slow and, on Shutdown, I see number of processes having to be
ended (explorer.exe, TeaTimer.exe, gcasServ.exe., ccApp, NVIDIA Twin, etc.).

Is there limitation with Explorer operations via a USB 2.0 external drive
when dealing with large number of large files? If this is not a
limitation... thoughts on resolving what I am experiencing or how to move
large files into a folder and working with them? Other thoughts/help?