Hello, does anybody know if exists some application for Windows XP, which is equipped with same funccionality as the AeroSnap in Windows 7 has? For example, if I drag a window in Windows 7 to the right edge of my screen, the window automatically holds 1/2 of the screen. Thanks.

Of course there is!
http://lifehacker.com/5085657/aerosnap- ... o-xp-vista

http://aerosnap.de/eng/download.htm tried this on a VM of Vista and it seemed OK, does the job so you could this and see if it works. Completely free but as it says it's beta software so it is "as is".

I'd recommend AltDrag; it lets you Alt+Drag windows Linux style (which I found quite natural while using the TrackPoint) and it will behave the Aero Snap way. It also lets you scroll a window without making it active, which is also very useful.

TrueTransparency can do it too, also contains Aero Shake. Doesn't need the bloaty .net framework, and skins your windowframe too.