I ran into the same problem here is how I fixed it:
goto [
go-pear.org] and copy the file as described below. The readfile didn't work for me so I just manually saved the page to a "go-pear" on my HD. Then I executed the "php go-pear" command (make sure you have php in your path or are in c:\wamp\php).
Follow the directions as go-pear executes and should be fine. However, note that for some reason wamp has 2 php.ini files, one in wamp\Apache2\bin and one in wamp\php. I don't know the *right* way to resolve this but I just made sure that the files were the same for me. The only thing the Pear installer appears to have put in my php.ini file is the include statement which is at the bottom of the file.
Everything works fine now...
# Installation: Windows
#
# On Windows, go-pear uses stdin for user input, so you must download
# go-pear first and then run it:
#
# Note: In PHP 4.2.0-4.2.3, the PHP CLI binary is named php-cli.exe while since
# PHP 4.3.0, it's simply named php.exe in the cli/ folder of your PHP directory.
# The CGI is also named php.exe but it sits directly in your PHP directory.
#
# > cli/php -r "readfile('http://pear.php.net/go-pear');" > go-pear
# > cli/php go-pear
#
# In PHP 5.0.0+, the PHP CLI binary is php.exe
#
# > php -r "readfile('http://pear.php.net/go-pear');" > go-pear
# > php go-pear