Thanks for posting this up to help others! You have shown what type of community this is, where people share their "ups" and "downs" so others may benefit down the road. 5 points for this very classy contribution :)
PS:You should be good to go with TFTP32. Many others have used this successfully for this upgrade.
The TFTP standard has an limitation on files greater than 32MB however several of the TFPT servers can handle this. Try using the newest tftp server from SolarWinds (free) or version 3.0 or later of Tftpd32. If you have a WCS version 4.1 you can use this for upgrading controllers as its builtin tftp daemon supports files greater than 32 MB.