On the note of RAM, it's probably old news to you if you tried to recycle 4x1GB for a new build, but for anyone else reading, I'll toss in one of the recommendations I made to a friend earlier this week. As a general rule, more physical sticks will lead to higher performance. Take two identical systems of 4GB memory, one with 2 sticks of 2GB, and one with 4x1GB. Assuming the chipset and data bus are wide enough to support it, being able to request data from four locations instead of two can be a major advantage, and needless to say, they'll both top out a single 4GB.
As for your specific situation, if you're not sure whether or not your board will natively support DDR2-1066, I will caution you that it can take a bit of tinkering (Voltage, CAS) to get 1066mhz RAM working up to snuff on a few boards. Since it sounds like you're pretty capable when it comes to putting a build together, as long as you're not afraid to get your hands a bit dirty and call in some help from search engines, it's really not all that complicated. Just figured it was worth noting so that you can do a little preliminary research if you go with a 1066 model.
