I brought a 2210 about three weeks ago. I was considering the 5550 but couldn't really justify the extra cost. The 2210/15 does all I need. Picked up a cheap 512Mb card for it. The speed is pretty good (games run well) and you get the dual slots for expansion so you could also pick up a WiFi card.

I'm slightly surprised at how good the bluetooth is. I picked up a bluetooth doogle for my computer at home and it links up quite well. I can stream music etc while out in the yard.

I'm sure the 5000 series is slightly better, but with the more compact size of the 2210/15 I can't see the 5550 being worth the extra money.