You absolutely can, and freezing is better, just keep two things in mind:
A. if you are using tap water, it is not sanitary. I've heard different opinions as to how much difference that actually makes, but it's a point to ponder. Tap water is also chlorinated, which can effect flavor. You can avoid both of these issues if you pre-boil your water, and freeze it in a sanitized container until use. But of course, it's more hassle.
B. You will need more water than you think, half the volume wont do it. I'll demonstrate this: Let's say you have 2.5 Gallons of boiling water (212 deg) and 2.5 gal of ice (32 deg) together you have 5 gal of water in a temp of (212+32)/2 =122<-This is the average temp. Too high. In order to get down to around 70 you'd need about 4 gal of ice to one gal of wort (212*.2 +32*.8=67. figure that wort boils a little hotter than water, so you're probably looking at around 69)
Now in reality that's not exactly true, because the wort losses the first 30 degrees or so in the two minutes after you turn off the heat, and another 10-20 degrees when you pour it into the fermentor. But still, I'd go with at least a 2/3 to 3/4 wort to ice ratio, and even then be prepared for it to be a bit hotter than you'd think