As has been said, it is all down to how you feel about it. I learnt to fly at Cardiff, which has a built in Xwind. The type of aircraft has quite a lot to do with it as well. For example, I have landed a PA-38 in a 28kt Xwind without any problems at all. I used to fly a Rockwell 112A, and the Max demonstrated Xwind is stated at 17Kts (I seem to remember) but I found that anything above about 11 was a REAL handful. I have never really had too much of a problem with PA-28's, but I guess that it's up to you. If you don't feel comfortable, don't do it. I, however have always found the 'challanging' landings are the smoothest because I have been concentrating the hardest. The ones where you have 2km of runway and no wind to think about are the ones I most often thump on, just because I'm not really concentrating on the job in hand. Why not go up with an instructor next time the wind gets up, and give it a go. I bet that you'll be surprised at just how much of a Xwind you can handle.