hi.. im interested in getting a Sony Vaio (why Vaio.. ? coz i just heart it <3) 

however.. im clueless bout which to get... 

looking for something that's not too heavy coz i travel alot... screen size that's not too small nor too big (probably around 13 inch? slightly smaller or bigger shud still be ok).. preferably 2Gb ram above... ok to game in (not too laggy and stuff)...

quite confused about all those different series type...  besides the screen size, what makes them different from each other?

thanks heaps in advance