The promotion changes very frequently. Sometimes free ram upgrade, sometimes free dvd-writer, sometimes free hdd upgrade, sometime free delivery, sometimes free graphics upgrade ... and combinations of those. So even if you pick the exact config as another person, the price may be different every week
To me, free ram upgrade to 1GB - not too attractive, cos they use 2 pieces of ram, I would rather go SLS buy 1 more piece of 1GB (then I can have 1.5GB, and can get another piece later to get to 2GB). Free HDD upgrade to 80GB - not attractive either, I would rather go SLS buy a bigger HDD (80 or 100GB) and use the original 60GB as external HDD. (But this one seem to be SATA, so might be harder to find external casing.) Free DVD writer upgrade - worth it, cos it's probably not easy to buy your own drive outside that fits perfectly, and you can't recycle the original drive easily. Free deliver - that's a $70 saving, you can't get replacement for that at SLS