howto check open ports ?

["Mehmet Fatih Akbulut" <mfatihakbulut@gmail.com>]

hi all,
i am now behind a firewall [at dormitory], and i want to check open ports. 
is there a handy program that does this job for me ;)
want to find an open port for apache to run. 
because 80. port blocked to people outside the dorm.
i both need an openport seeker program and info if apache will work let's say i change its port from 80 to 5055 [assuming this port is open] ?
many thanks in advance.

Cheers,
MFA