which clubs do i take?

I now have 2 sets of irons my mx17 and mp 57's tonight im playing in a little match to win 3 balls not inportant so im playing with my mp 57 that i only have played 4 holes with before.
I play matchplay tommorrow night and in a big ish torniment on saturday. which should i use for them? My MP 57s that im still getting used to, or my old mx17 that are ok?
and will using them both at different times just throw me all to cock

Never go back.  There's always an excuse to regress, but all you'll end up doing is messing up both sets.  Bite the bullet and only take the new ones form now on.

Got to be the new gear Matt..

In readiness for our Society bash next Saturday..

Now now Matt.....

Tears to the eye's bud...

"what' a 2 iron?"

Impossible to hit unless you have a proper swing.  You should not be allowed to buy one unless you can produce a handicap card that shows you are below 18.  They should be stored under the counter in plain brown paper.  Selling one to a 25+ handicapper is like selling a one legged man a bicycle.  Shops selling to 18+ handicappers should be punished under the same laws that prevent the selling of cigarettes to under 18's. 

It's like giving a hammer to a toddler and telling them to have fun.  There's a slim chance you'll get a new set of shelves on the wall, but it's much more likely that the same wall will be full of 1" hammer shaped holes at or about toddler shoulder height.

Get yourself a 1 iron ya wuz!  I've got one (but never use it), can hit maybe 1 in 10 properly with it but by god it goes.  Worth it for amusement value

A wise scholar once said that you should always use a 1 iron in a thunderstorm, the reason being that even God cannot hit a 1 iron !!