Is it possible to install an SSD Drive into a Macbook Air if you purchase it with the Parallel ATA Drive?

Can anyone tell me if this is possible? I recently chatted an Apple Representative and didn’t get very far (See below. I’ve changed the name for obvious reasons). I don’t think they were allowed to say whether this is possible.

Hi, my name is [AppleRep] Welcome to Apple!
You: Hello [AppleRep]
[AppleRep]: How may I help you today?
You: I am trying to figure out two things: 1) If I get a Macbook air with the Parallel ATA Drive now, can I install an SSD later?
You: and 2) Can you tell me how much RAM the Macbook Air comes with?
[AppleRep]: Good question and I am happy to assist, Apple doesn’t upgrade internal hard drives after purchase and the MacBook Air will hold 2 GB ram.
You: Okay. But is the drive upgrade possible?
You: I want to buy the air but I dont want to pay 1000 for the drive because I am sure they will come down in price and increase in space soon.
[AppleRep]: Apple doesn’t upgrade hard drives after purchase.
You: yes. you told me that. but is it physically possible?
[AppleRep]: Since Apple doesn’t do that I can’t make a recommendation there you would be welcome to check with an Apple authorized service center to see if they could do that for you .
You: I am not asking you recommend anything. I am just asking if it is possible. If it is not, that is okay. I just want to know.
You: And if youre not allowed to say, thats okay too.
You: but a definitive answer would be great.
[AppleRep]: You would need to work with an Authorized reseller this chat only supports sales of Apple products and configurations that we sell so I am sorry but I don’t know.
[AppleRep]: If you want that drive I would recommend getting it at time of purchase.
[AppleRep]: We do offer financing .
You: Thanks.