Why would you install an ITG2 skin? Just download OpenITG: http://openitg.gr-p.com/
The defaults on it should be basically the exact same as an ITG machine

Go to Jeffrey1790.com to get OpenITG PC Beta 2 version

Same as the arcade version down to the wire. Just some features are taken out, and some are added in. Like a step editor and stuff.

Not that it is too much concern. It is a beta after all, and will crash sometimes.

Thanks for the links. But still doesn't answer my question lol. I'm just really curious about the math

haha yeah. Well I think it is scored differently because SM is based around DDR scoring not ITG. Even with that ITG2 theme it's more of just a skin than anything else. If you want ITG I would just go ahead and download OpenITG

DDR dance points:
A "Perfect" is worth 2 points
A "Great" is worth 1 points
A "Good" is worth 0 points
A "Boo" will subtract 4 points
A "Miss" will subtract 8 points
An "OK" (Successful Freeze step) will add 6 points
A "NG" (Unsuccessful Freeze step) is worth 0 points

ITG Scoring:
For each judgement, the player receives or loses points depending on their accuracy:
Fantastic: 5
Excellent: 4
Great: 2
Decent: 0
Way Off: -6
Miss: -12
And for holds and rolls:
Yeah: 5
Bad: 0

Stepmania either emulates the DDR settings or does something totally wacky.

That DDR scoring is post 5th mix right? I know 5th mix is alot different, misses hurt your score ALOT. Extreme 1&2 US both have 5th mix scoring and let's say for example a song should've had a score around 97mil, but because of 1 stupid miss, you get like 91mil

I think SM does emulate DDR settings when it comes to the DDR style scores, but percentage scores aren't like ITG at all. Matter of fact, I think they're a little wacky. On Warcry of Salieri I have 97.57mil and as a percentage it's 93.72%. Then on Blaze, I have 97.33mil, and the percentage is 94.37%. I mean, since Blaze has a lower million score than WOS, shouldn't the percentage score be lower than 93.72%? I'm able to see both thanks to this one theme

Oh and that reminds me, those percentage scores are the ones show up on the ITG 2 themes, so I'm pretty sure they're not the same as actual ITG percentages. I think the ITG score would be alot closer to the DDR style scoring. Like for example, my score for WOS on ITG would be around 97.57%

4th/5th machine scores were combo based.  Higher combo = each step worth more.
Grades were based on...  I'm not sure pre-MAX.  All perfects and full combos had their own grades, but not sure how other grades were assigned.

Max~Extreme is what kevin said for grades.  100%=AAA, 93% =AA, then something like 85 for A and lower for B/C.  D = passing below C threshold.  Machine score is based on each successive step being worth more (step one = n, two = 2n... so on, with a bit more for freeze arrows (they add to "current" step count)), with a max of 10000000 on max and diffx1000000 for max2/ex.  perfect is worth n, great is worth n/2.  On extreme nonstops, machine score is n for marv, 9n/10 for perf, n/2 for great.  During onis, marvs are 3, but for nonstop grade calculation, they are still 2.  Oni scores are of course, actual/max possible on max2 and marv*3 + perf*2 + great + ok*2 on extreme.

Supernova is perf/ok = 2, great = 1, with the same machine score calculation as max.  Grades are based on machine score, 1000000 = AAA, 950000 = AA, 900000 = A, and more below that I don't know thresholds for. On nonstops, marvs are worth 3, and this means marv = n, perf = 2n/3 and great = n/3.  However, the grading scheme is unchanged, and this is why AAA is for all intents and purposes impossible, and why AAs are much harder to get on nonstop courses.  Oni scores are score/max score.  The marvelous being 3 vice 2 is why oni scores on max2 were so much "better"

Supernova2 is same as supernova, except marv in normal play is worth n minus 10.  All perf/marv is a AAA regardless of perf count.  So a AAA can vary anywhere from 1000000 to 1000000 - (stepcount*10)

I'm done now.

ok, so this is kinda half on topic, but whenever i try to go into the graphics option in openITG (just downloaded it), it always gives me an error, and how do i do the patches?

NOTE: there seems to be a problem with the home theme metrics, a parse error in ScreenGraphicOptionsBasic::Line8. If you run into this, just go into Themes/home/metrics.ini and change "LineNames=1,2,3,4,5,6,7,8" to "LineNames=1,2,3,4,5,6,7" under [ScreenGraphicOptionsBasic].

http://www.stepmania.com/forums/showthread.php?t=14050