Changing computer settings

[IxYoYoxIv3]

Hello all, I just want to let everyone know I am new to this forum but I plan on posting and reading often. I have 98 Monte 3.8 z34. I have been toying with the idea of getting a new computer or race chip (excuse me if I seem like I don't know what I'm talking about, it's cause I don't) But someone down at an auto parts store said that depending on what I want to do, I might not need to get a chip I could just get my computer reprogrammed. He said it would reset my speedometer (i have custom wheels on the car) and there are other things I could do by reprogramming it.

Any input on getting a chip vs reprogramming?

Thanks in advance