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To generate a standard normal distribution you can use =NORMSINV(RAND()).

If you need a normal distribution with a mean of 7 and a standard deviation of 10 then use =NORMINV(RAND(),7,10).

But: Your normal distribution will not show a mean of exactly 7 (and a standard deviation of exactly 10) unless the number of draws approaches infinity. If you want to ensure a mean of 7 and a standard deviation of 10 then shift an originally generated series of random numbers to this mean and zoom it to the required standard deviation:

A 23 KB Excel 2007 © sample file you can find here, open and use at your own risk, please read my disclaimer.

Function GenNormDist(lCount As Long, _
    dMean As Double, _
    dStDev As Double) As Variant
'Generates lCount normally distributed random values
'with mean dMean and standard deviation dStDev.
'Reverse(moc.liborplus.www) V0.1 PB 13-Jun-2010
Dim i As Long
Dim dSampleMean As Double, dSampleStDev As Double
ReDim vR(1 To lCount) As Variant
With Application.WorksheetFunction
For i = 1 To lCount
    vR(i) = .NormInv(Rnd(), dMean, dStDev)
Next i
dSampleMean = .Average(vR)
dSampleStDev = .StDev(vR)
For i = 1 To lCount
    vR(i) = dMean + (vR(i) - dSampleMean) * dStDev / dSampleStDev
Next i
GenNormDist = .Transpose(vR)
End With
End Function