Yeh if the price isn't much different, then go for it. Although having 2gb more ram than needed will make the battery life shorter.
I just opened FireFox, Dreamweaver, Photoshop, Word, MSN, Winamp, uTorrent, KeepNote, Access, Excel, Groove, Visual Studio, OneNote, Outlook, PowerPoint, iTunes, Fireworks and Flash, and it's only using 2.22gb.
It's up to you, 4gb will make a difference, but very small. The main difference will be the battery life really.
I hate Acer, the feel really tacky, usually look terrible, customer service isn't great... Never actually owned one though so don't take it as read.