How many users will there be - you can use windows xp as a print server but I think you can only have a maximum of 10 users sharing the printer at a time.
If you have less than 10 users a normal PC with at least a Pentium 4 and 2GB ram should be sufficient.
Can you be more specific about the flight packages so I can advise on suitable server and OS for them?
If you live on the Gold Coast my company can assist you with the purchase and setup of a server for your needs at a very low cost. You can contact me at my website.