Can I use iPhone 4 MicroSim card in any other Unlocked cellphone?

Title says it all, but basically, will I be able to use my iPhone 4 MicroSim [with fullsize SIM card adapter I assume] in another unlocked cellphone like those cheap no-plan phones at like Walmart?

Whenever I go out exercising, hiking, playing ball, etc. I like to have my phone on me, but I feel uncomfortable whenever I bring my iPhone 4 on those rough-and-tumble activities. So, as a compromise, I was thinking about getting a really cheap phone with some basic functions (texting mainly, though having a music player would be welcome too) that I wouldn't mind if it got knocked about some accidentally. Speaking of, does anyone have any suggestions for a cheap (under $40 total, including tax/s&h) phone like that?

Also, if I got a new substitute phone that was able to browse the internet, would my current iPhone data plan cover it? Can I use the iPhone 4 MicroSim in a non-3G phone in general?

Also, do any brick and mortar stores sell those fullsize SIM adapters or would I have to look online for one?

Thanks for the help!

 

Thanks for the help guys. Just got back from shopping, and although I didn't buy one at this time, I did browse some of the cheap cellphones that were on display. In between prepaid Gophones and Tracphones though, I'm sorta confused. I asked the employees that worked there whether I could use my own SIM card in those phones, but they didn't know. Anyone have a clue about this?

I'm mainly just unsure how the "prepaid" minutes might or might not conflict w/ using a SIM card and if those phones even had SIM card slots to begin with.