PHP 5.0.1 does NOT return a string for curl_version -- it instead returns an array in this format. (Values are for my dev box at the time of this writing, your results will vary.)
Array
(
[version_number] => 461570
[age] => 1
[features] => 541
[ssl_version_number] => 9465935
[version] => 7.11.2
[host] => powerpc-apple-darwin6.8
[ssl_version] => OpenSSL/0.9.7d
[libz_version] => 1.1.3
[protocols] => Array
(
[0] => ftp
[1] => gopher
[2] => telnet
[3] => dict
[4] => ldap
[5] => http
[6] => file
[7] => https
[8] => ftps
)
)