Well I'm running a server which is very like pa40's suggestions except for the fact that its 35X and its running l2j which I know most of you hate, but its actually improving alot and is getting much better every day.
Were running on a dedicated machine with great specs such as:
Processor - AMD Phenom 9750 Quad Core @ 2.4GHZ
Ram - 8GB
Video Card (Don't think it matters) - ATI Radeon 3870 HD 1GB
OS - Windows Vista Home Premium 64-bit
120GB TeraByte Hard drive @ 10000RPM
Internet Connection
on speedtest.com
-Download 23.00Mb/s
-Upload 1.00Mb/s
Visit L2Angelic.com for more info
Only thing that I really need to upgrade is my internet connection which can be done with one call to my provider but before I do that I would like to know if there are people playing on the server since no one has been joining lately.