well, i took the server.dll and replaced it from the above archive (didn't touch the client pc) and everything seemed to work great!
i'm quite curious as to why these binaries (client.dll and server.dll) are different from the ones packages in the zip archives on the main download site? both say their 1.9.3, but for example there's almost 1.5 megs of difference in file size alone between the two client.dll files. i couldn't tell too much difference between the two with a quick look in a hex editor or too much difference between the strings. i'll poke around some more when i have time
but for now i fired up the server the same way i had before with the replacement server.dll - then fired up steam on my client pc connected and was in the game!
Thanks again for your help

any ideas as to the differences between the dll's in the zip files listed and the binaries you linked to? (i also noticed that the mirror with those binaries was the only one to offer the setup as an exe)
time to play some sourceforts! w00t!