If you want to "roll your own" using Excel, try this:
enter in Excel in four adjacent cells (assume 5 holes on a 3.5 inch radius here):
num______5
radius____3.5
A trick: Formulae are easier if you name variables. This will allow you to enter "num" and "radius" instead of something like B2 and B3. To name the two cells containing numbers, highlight the four cells above and use Alt-I, N, C (Insert, Name, Create.) Excel will ask you if you want to name the cells on the right (the cells containing the numbers) using the names are to the left. You want that: hit enter. Now, when you enter "num", or "radius" in any cell it represents the numbers in the named cells.
Now enter the following name and formula in two separate, adjacent cells:
angle______=2*pi() /num
Note that Excel uses radians as it's native degree measure. There are two pi radians in 360º. You just used your named variable, num, to divide the circle into num equal sectors.
Highlight the two cells and use Alt-I, N, C, enter to create then name "angle".
Now enter HoleNum, 1, 2, 3, 4, and 5 (assuming five holes again) vertically, in a column. If you highlight everything you just entered and use the Alt-I, N, C , enter trick Excel it will create a variable called Holenum. For now, assume that the center of the circle is at the 0,0 xy position. Create an Xcoord and Ycoord column (e.g. , put these names to the right of HoleNum) and enter the formulae:
In the Xcoord Column: = sin((HoleNum-1)*angle))*radius
and in the Ycoord column = cos((HoleNum-1)*angle)*radius
So you've entered:
num______5
radius_____3.5
angle______= 2 * pi() /num
HoleNum____Xcoord________________________Ycoord
1__________= sin((HoleNum-1)*angle))*radius__= cos((HoleNum-1)*angle)*radius
2__________= sin((HoleNum-1)*angle))*radius__= cos((HoleNum-1)*angle)*radius
3__________= sin((HoleNum-1)*angle))*radius__= cos((HoleNum-1)*angle)*radius
4__________= sin((HoleNum-1)*angle))*radius__= cos((HoleNum-1)*angle)*radius
5__________= sin((HoleNum-1)*angle))*radius__= cos((HoleNum-1)*angle)*radius
When I do this I get:
Holenum Xcoord Ycoord
1____0.000____3.500
2____3.329____1.082
3____2.057____-2.832
4____-2.057___-2.832
5____-3.329___1.082
The above assumes that your first hole is "on top". You could swivel the hole pattern radially by adding and angle offset to all of the sin and cos formulae if you want. For example, if you want the hole pattern flipped 180 degrees, add pi to each of the formulae, e.g.
=cos((Holenum-1)*angle+pi())*radius
You could also create Xoff and Yoff offsets to change the center of the circle:
Xoff_____1.5
Yoff_____2
After naming these values you'd add the Xoff to all X values and Yoff to the Y values. To whit (for Ycoord)
=cos((Holenum-1)*angle+pi())*radius + Yoff
Anyway, if you have excel this might be easier to do than learning a new piece of software.
Before I used these to drill holes, I'd highlight just the Xcoord and Ycoord numbers and use the Excel plot (Alt-I, H, X, to Insert, cHart, XY) to do a sanity check.
Good luck,
Jim