I too am building a jukebox very soon .... I find that depending on what you have, (and want to spend) will determine the setup... for example i am purchasing a touch screen monitor, using an old Pentium 4 pc with a 250 gb hd and building a simple compact juke with touch screen support.... i am then running the sound (from a simple pc 1.5 mm stereo jack) to a wireless audio transmitter/receiver to my home stereo (B&W system)....
For my "chassis" I will be building a bar top arcade style terminal, with fans and maybe some cool lighting....
As for your question about what is the "best way", it all depends on your own preference... anyway will work!! You can build a larger chassis and mount speakers on/in it... you can simple put pc speakers in it (good ones obviously) or do what i plan on doing and skipping the whole "in juke" speaker system and go externally... also "juke setup" can change things as well... if its an "in wall" setup you can easily to a cable run to an existing amp...
Portability also makes a difference... with the amp and speakers setup internally you run into weight issues and such so moving it can be a pain... plus with mine i'd like to be able to bring it to parties and such.... ill bring the tunes they supply an amp/speakers....
What kind of button were you planning on using? like arcade style or.... I imagine you can do a mame style button setup with an ipac and arcade pushbuttons with custom button labels (
http://forum.arcadecontrols.com/index.php?topic=64645.0) or go my route and use a touch screen and get rid of all buttons....
I am going to be using:
Freebox (eventually get upgraded version) (
http://www.freeboxjukebox.com/Forum/index.php?board=5.0)
The Amphony Model 1500 Audio Transmitter/Receiver (
http://www.amphony.com/products/l1500.htm)
Elo 17" LCD Desktop Touchmonitor (
http://www.elotouch.com/Products/LCDs/1715L/default.asp)
Compaq Presario P4 pc with 250 GB HD
My carpentry skills