damien, learn to do a search for anything u doesn't know. if u can't find, then try asking here.
what ST1100 said is correct.
DSLR with buffer.
U take a shot, shot is 'worth' 1mb, the cam stores the 1mb in the buffer, a buffer is like RAM (temporary storage), the buffer transfer the 1mb onto your CF card. Rate of transfer can range from 1mb/s to 6mb/s...all depends on the camera, AND depends on your CF card writing speed. if writing speed is abt 1mb/s (about 20X? can't rem now), then your buffer will clear in 1second, and u can snap again.
But most DSLR have many shots available in the buffer, 300D has 4, and D70 has 'unlimited' buffer.
It is only when this buffer is full, (when u take continuously), then the effect of the writing speed matters. for eg: buffer can take 10 shots, total 10mb, buffer is full, say the cam can write super fast 10mb/s, but your card is super slow, 0.1mb/s, then it'll take 10seconds for the 1st pic taken to clear, and then u can take another pic, and wait and so on.....
thats the DSLR take.
for non-DSLR, there's usually no buffer, hence is its 'more important' --> subjective term, to have a higher speed CF card, so that u can take another picture again.
Best way is to go to a shop, bring your cam, and stop watch, and time yourself.