I think Topscore is one of the best DAT prep out there. I wouldn't study for the DAT without it. I suggest buying it used or just borrow it from someone. Topscore says that the CD only works for 6 months after you purchase the CD. This is true and your computer recognize this because of the system date in your computer. However, here's the trick: you can reset your computer to a date that is within the 6 months of when the CD was purchased. In essence, your grandchildren can use this CD in the year 2050 as long as you set the computer date within the 6 months of purchase!!! Pretty Cool, heh!!! Good luck to all! Keep it on the down low before TopScore figures out a way to go around it! hehe.