[oldkim]

Try both.

Only you can know which is best for you.

Both are a "game" competition for handgun. One focuses more on self defense (IDPA) the other run and gun (ISPC/USPSA).

IDPA:
Holster is concealed (some type of cover is used)
Scenarios are more self defense oriented
Strings of shots are less
No gaming before - you just shoot the scenario
No special equipment other than concealed focused gear (no lasers, etc)

USPSA (aka IPSC)
Fancy holsters - quick draw
Scenarios are open - runs the gamit
Lots of shooting
You can "game" it to shoot faster
You can dress up your gun and gear to what your wallet will allow

Both: FUN!
Focus on "score" which is derived from how fast you shot and how accurately. You can shoot fast but if you can't hit squat - your score is still not good. But same for you can shoot accurately but shoot slow - your score is still not good.

For you just getting into the shooting sports - try them out and just have fun. You'll figure what works for you and why.

Good shooting!