US has different voltage (110-120V) AND different frequency (60Hz), as well as the physical plug being different.
- Alarm clocks that plug in will run too slowly here, as they rely on frequency to keep time. It's 50Hz here. There is no point in bringing them.
- Computers and other high-end products MAY be able to handle European V and Hz. Check the power supply. It will say something like "100-240V" and "50-60Hz" right on there if it will work. This means you just need to convert the physical plug. The power adapter does the rest.
- TVs and VCRs will not work. Don't bother.
- Other stuff will require a fancier unit to change the voltage, and for cheap stuff like blow dryers it's usually not worth it. If you have a lot of small stuff, consider bringing an American power strip and putting the converter just on that.
I definitely agree it's easier to find everything beforehand. Good luck with your move!