that depends...go to guitar center/sam ash/whatever and play around with the hardware. you could go the triton/motif/fantom route or you could go the mpc route etc. i'm not sure if you can sequence hardware in acid pro though...ask questions of the people that work there and get a good feel for hardware and if they got other software, try that out too...because nowadays the issue of things working better with others is relatively nonexistent...everything is almost on the same level and it boils down to personal preference...so you just gotta figure out what you prefer ya feel me? my suggestion though, first and foremost and before you think about getting hardware, make sure you have a solid bit of software. I'm not bashing acid but i would suggest something like cubase, reason, or something like that. once again its really all on you though