download WINUHA and install it.
right click the .uha file on your desktop and select "extract to \files\"
delete what you wanna delete (I suggest eth* and en* files...should slim it down enough...the original is 1135kb and deleting those 3 drivers would make it 1121kb)
open up winuha, browse to the folder it's all in, and hit CTRL+5 which selects all items. Note, that's a 5, not an 's'. Then click "add selected" at the top.
don't change any options here...click Advanced, check the command line option, delete the defaults, and add the following command line from his website without "winuha" at the beginning.
NetBootDisk.com - The Universal TCP/IP Network Bootdisk for M$ Networks for the command line to recreate the UHA file...just use:
a -y+ -p- -r -mx -ac+ files.uha .\zip\*.*
you also may have a corrupt/old download of netbootdisk.