the key differences between the 7230 and 7290 is that the 7230 lacks the 850Mhz band in the United States and 7290 is quad band (800/850/1800/1900). so you may notice the 7230 doesn't penetrate building very well in some cases. also the 7230 has half the memory (16MB vs. 32MB) of the 7290. This is a big deal when you are storing 30 days or more of emails and call logs - one tends to exhaust the device memory, and for some reason garbage collection of memory was poor on this model (from my recollection) and caused some problems as a result. But maybe a later O/S revision fixed that.
but if the phone is to be used for light texting and the occassional phone call (like you mention) then either device is probably fine.
BlackBerry - BlackBerry 7290 Wireless Handheld Device | With Quad-Band Smartphone, Bluetooth & Email
BlackBerry -7230 - Archived Devices