Jimmy,
 The answer is "it depends" only because I don't know what your target temperature is!
 You can set the grain/tun temperature by pressing on the "Details" button next to the mash profile name in a recipe and then setting the grain/tun temperature.
 BeerSmith assumes that both the grain and the tun are at the same temperature.  However, when I tried it with both a 55 and 66 F setting the difference in strike water temperature was about two degrees.
 For a Single Infusion, Medium body (154 F step, 1.25 qts per lb) I came up with 166.8 assuming grain/tun are at 66 F and 168.4 assuming both are at 55F.  The true value is probably somewhere in the middle, but the grain is the dominant factor (13 lbs of grain vs a 4-5 lb mash tun) so I think somewhere around 167+ would be perfectly acceptable.  I personally have trouble reading much closer than a degree on my thermometer in any case.
 I do recommend taking a look at the equipment setup article as well...
 http://beersmith.com/equipment_setup.htm
Cheers!
Brad
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