Sorry Norio, i forgot to mention that, in addition to what Francis said, MIDI is definitely the way forward for effects..especially since we're slowly but surely moving towards complex effect chains and the quest for pristine tone.
Checking out Petrucci's or Steve Lukather's setup and the Roland GK Synth stuff will provide you some valuable info on the workings of MIDI. And taking it a step further, Godin (By far my fave bunch of luthiers...and John McLaughlin's) have been intergrating synth access since their prototypes of the Multiac Nylon (insanely delectable guitars).
Also, to get an all rounded eye-opening view of MIDI, i have attached the link to the Godin guitars' "What is midi?" section
http://www.godinguitars.com/whatismidi.htm
Trust this info will help you...but like you said, if you've got limited options with regard to gear, play around a little to get your signature sound.
Happy hunting
PS - And Satch does use a Boss DS-1, which he sometimes switches with a blues driver when he feels like it. I'm not sure about the Mesa Boogie stuff though.