n0nsensical

Assuming the same timings, two RAM sticks shouldn't be slower than one, and if your motherboard supports dual channel they'll be faster. It doesn't matter where data are physically located in the RAM because lookups are in constant time based on the timings anyway. (Again except in the case of dual channel where the physical location does matter, but you can only have a speed INcrease from that.) Think of phone books. Whether you have one giant phone book with A-Z or two books split A-L and M-Z doesn't matter because you know which one to grab from the start. The advantage in having one stick versus two is that you have an extra slot available for future expansion.

That said, motherboards don't necessarily support the same timings for all of their RAM banks. If the additional stick needs slower timings then yes it will be slower compared to one fewer. In any case, dual channel or not, slower timings or not, there's not going to be much of a difference in real world performance between RAM configurations for most purposes. The fact is RAM accesses are so slow compared to your cache and CPU that even if you make them slightly faster they'll still be orders of magnitude behind. Having too little RAM is a much bigger problem than having slightly slower RAM and to answer the original question, I would definitely go for the 1 GB. I have 1 GB and even that's not enough to avoid swapping to disk.

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