Thanks for the quick replies..
Where could I find exactly which crystal and capacitors I would need? Being able to program the chip whilst it's sitting in the Uno board, and then just taking it out after that would be the most simple way I would think, at least until I get a better understanding of how the circuitry works.
I can't leave the Uno in my project, as it'll be too big..
What I'm doing is creating an Advent Calendar for my nephew, and what do all kids love... Things that light up. So I want to use an Arduino to turn on a light which corresponds to the door of the advent calendar that he can open on that day (so 24 lights for 24 days leading up to Christmas). Anyways, I've bought a DS1307 Real Time Clock off eBay (http://www.ebay.com.au/itm/New-Arduino-I2C-RTC-DS1307-AT24C32-Real-Time-Clock-Module-AVR-ARM-PIC-/230755266711?pt=AU_B_I_Electrical_Test_Equipment&hash=item35ba15f097#ht_4179wt_1139), which will keep an accurate time for me. All I need the Arduino to do is turn on the correct LED when the time is right (all of which I can program, the software isn't a problem). So as for having it run on 16MHz or 8MHz, I don't think it would matter too much?
What would I need a reset button for? Would that be as simple as adding a push button to pin 1 of the chip?
Thanks again for the replies