hi Jokerswild,
i'm not a programmer to teach you about perl/cgi...
i'm just like you... but maybe i got this info early than you.
before i continue on, please answer this...
1) are you on a free hosted site like tripod.lycos.com?
2) or do you own your own domain name, and also paid hosting service?
if you answer 1) and that it is tripod.lycos.com, then you probably didn't aware of "custom scripts"
which are not allowed to be hosted on free tripod.lycos.com sites.
but you actually can make your own - not just modifying with the original left intact, but modify it
and make additions to it as well - provided that it is ALLOWED.
i'm on tripod, anyway... and i did try before, i guess somewhere on may/june this year.
and it works well - i mean it, nothing's wrong happened.
but, i'm not sure how is the guestbook script did you mention here looks like - afterall it makes not
so much differences.
and either your answer is 1) or 2), the following might be the reasons...:
it might because of your script - perhaps there's a bit misconfiguration you did into it which leads
to that problem.
at the very least, try to ask your system administrator - the staffs at your hosting company.
they supposed will be able to give you some ideas, so that you're able to solve it.
it might happened because of their server - for whatever it is/are.
or why don't you just try to send a message to report it to Matt - the author?
if you get a "page cannot be displayed" error, it usually happens because of either one or two of the
following:
1. the web page is not existed
2. the web page is not accessible due to some server problems, as mentioned above
3. your script is not configured correctly, as mentioned above
[and there might some more which i don't know]
and about ftp uploading, i guess most ftp softwares today, such as filezilla and wsftp, are able to
automatically change the uploading method - either binary(mostly for images) or ascii(text-based).
however, since you said that you used the one that is built into Windows(i think it should be telnet),
then i'm not really sure of it as i don't have a telnet access - not on tripod.lycos.com free hosted site.
okay, so what i'm saying here...?

nothing but some hints which you might haven't yet known.
read my post carefully, and see if you can find the causes of your problem here.
and... does your hosting provider offer sendmail? not all web hosting which support perl/cgi have
this program installed - just like tripod.lycos.com, but they have a ready-made/pre-made perl
modules[.pm] which will do just the same.
if you have configured, or if it is configured to work ONLY if sendmail is available, then you have to
concern about this too...
and by the way, you may want to visit
http://www.htmlgoodies.com/ to get a free guestbook which
comes along with a nice tutorial - you can choose to get their guestbook script, or their bbs script,
or both - believe me, it's not so hard to modify those scripts - woops! i'm not altering copyright, okay?...
until then, good luck with your guestbook script!
[ p/s: if it still doesn't get to work, why don't you just get a new one?...

]