http://www.dopdf.com/download/setup/dopdf_7_0_330.exe
ist the latest edition for W2k,
while the current doPDF 7.3 ( available at the Download Mirrors )
just runs on WinXP and newer.
I did not test 7.1, 7.2 as there is no download offer here.
So the claim "Free PDF converter - doPDF7.3 for Windows 8, 7, Vista, XP, 2008/2003/2000 Server (32 and 64-bit)" is not true anymore

please either compile your software so that it can be executed on W2k,
or change the claim to
"Free PDF converter - doPDF7.3 for Windows 8, 7, Vista, XP, 2008/2003 Server (32 and 64-bit)"
Sincerely
Rolf