I just went from 2X256 to 2X512Gb ram on a nearly 8 year-old Dell. It does make a big difference in performance! I haven't done it before because DDR ram has become expensive (being an old technology). I bought it used on CraigsList (got lucky). This guy wanted $10 for 2 sticks and sent them to me to try...before buying! Well, they worked great and I sent him $25!
Anyone who has search for memory will soon realize a price listed (say, PriceWatch.com) is a generic high-density and one recommended is a third more and low-density. So you end-up paying a price similar to NewEgg...then why bother. (for what I got, NewEgg price for 2X512 DDR would be 60 to $70)
Excellent, Alan. Adding RAM is the one thing that helps speed up a system. The only other limiting factor (other than the motherboard itself) is the CPU.....