You should always add error checking when working with sockets, especially in the sockopen event. The sockopen event will trigger, even if the connection failed, so you should check for $sockerr there.

That regex is very excessive and not necessary, the following will do fine, if you change your get to:

GET /get.html HTTP/1.0

if ($regex(mirc,%temp,/Download mIRC (\S+) or/)) {
echo -a Version: $regml(mirc,1)
sockclose $sockname
return
}

As you can see, I do a socklose after a match has been found, as it's no longer necessary to retrieve the rest of the data.

Btw, why not use a local variable %temp instead of a global one? Right now your script leaves a trailing %temp global var.

Furthermore, it would be a very good idea to create a while loop checking for $sockbr, and to read more from the buffer in the same event, than letting the on sockread even trigger. Letting the event trigger is slower.