I(and many others too) have got the same problem as mentioned in http://bugs.php.net/bug.php?id=19591.

I'm running PHP 4.2.2 with Apache 2 on Win2000 SP3 and I _have_ an
original winnt\system32\msvcr70.dll, perhaps form SP3. I also have the
php_curl.dll in the correct folder, all other modules work well this
way! I also have the "real" curl run on my computer, therefore I needed
the other required dlls in system32 folder, so if curl works, php_curl
should work too! I also copied all related dlls into serveral folders, but nothing worked. I think this _is_ a PHP-bug! I get the same error as described
in the following:

<quote from php-manual:
http://www.php.net/manual/en/ref.curl.php#AEN9715>
orangevwbus at yahoo dot com
05-Jan-2002 08:12
In win32 (Windows 2000), I couldn't get apache to start with PHP/curl
support 'cause it said it couldn't find the php_curl.dll. Well it was
there.
MSVCRT.dll was there as well, but after I ran the dll through "Depends",
there's a new DLL for the Microsoft .NET stuff. It's called msvcr70.dll,
and without it, php_curl.dll won't load.
I didn't want to load .NET framework on my machine (which
msdn.microsoft.com suggested)
I did a google search and found a downloadable copy of the file and
threw it in my %system%\system32 folder and all the lights and whistles
came on.
d dot kingma at ContentS dot nl
30-Jan-2002 08:47
in addition to the files named above, you should also add the file
libeay32.dll to your PHP directory. The file can be found in the dlls
directory
</quote from php-manual>

And please have a look at
http://curl.haxx.se/mail/archive-2001-05/0058.html 

rgds
Andreas