I just use WinRar and split the file into 2 archives. I know there's at least a trial version out there, but I'm not positive since I'm still using the version I picked up a few years back (no real need to upgrade, so I haven't).
7-Zip is another program that you could use to make a multi-volume archive file. It can save in ZIP format and many other archive formats. Also, "7-Zip is free software distributed under the GNU LGPL".
Actually, the last time I tried this, I found that it didn't work. WinZip will create multiple files by grouping individual files into archives. WinRar on the other hand, does a straight binary split of one or more files into multiple .rar files.