Go for the RAM
OK, here's my take on this, based on years of experience with various PCs (I'm now using my first Mac!): go for the additional RAM right from the start, as that will affect every aspect of the machine's performance. Some software is pretty RAM-intensive and it does make a difference to have as much RAM in there as you can afford. DVD burning and video editing are definitely RAM-intensive activities. I would choose the 1 GB chip and that way you've left the other slot open for later on when you might want to add another 1 GB. Getting 2 512s is going to mean that later on when you do decide to upgrade that you'll be wasting one of those chips. When I bought my iMac at the Apple store and said that I wanted to max out the machine with 2 1GB chips, they "bought back" the 512 chip that was initially in the machine. Nothing wasted and now I don't have an extra chip floating around here unused the way I would've had I gone ahead and waited to upgrade the RAM myself. Yes, it costs a bit more to have Apple upgrade the RAM chips but my feeling on this was since I was buying a brand-new machine, might as well go all the way and have it done, then I wouldn't have to worry about it, and if there were problems the machine and the RAM are both under warranty and it would be their responsibility if they'd put in a bad chip. Happily, everything is working great in this machine, no problems...
I have also just ordered a 15" PB and again did the same thing, maxed out the RAM (2 GB), and now I will be assured of maximum memory performance from the get-go and won't need to worry about upgrading it further down the road. On both the iMac and the PB I will be doing Photoshop, Dreamweaver, etc., as well as burning DVDs. Even when doing basic day-to-day computing activities, the increase in RAM is noticeable.
In your situation, go with the 1 GB chip in the one slot so that further on down the road when you're ready to pop in more memory, you'll have that free slot ready to go and there will be no waste the way there would be if you pull out the existing 512 MB one.
As for the hard drive issue: I'd stick with the hard drive configuration and size that you can afford -- the standard 80 GB should be fine for a while -- and put the money into the RAM. Later on down the road you could always add on an external hard drive (and this is usually recommended anyway for providing a safe backup to your system and data).
Good luck! I'm waiting for my new PB to arrive later this week.
OTB
