I want to upgrade the memory from 1GB. I've looked around here and picked up some conflicting info. So maybe a few of the helpful experts here can help. Here's what I've read.
1. We can add 2GB of DDR533 (PC2 4200) 200 pin memory in the DIMM slot #2. Since there is 512 in slot #1, the means there will be 2.5GB in the computer. Windows will only see 2GB. But that's okay because according on one poster here, the system will allocate some of the xtra 512 to system functions. Maybe even video will get a boost from this available resource. Does this sound right?
2. The User Guide says that 512 can go in one slot and 1GB can go in the other. The guide does not specify PC2 4200, but I assume that's what it has to be. Now, why would the guide say only 1GB can go in slot#2? I really want to try the approach in 1 above, but I don't want to waste $ by buying a 2GB chip and find out it won't work in the laptop.
I bought an off lease D420 two months ago. It was refurbished by Dell. It came with the latest bios update & 2.5GHz memory. As far as I can tell Windows XP Pro SP3 can "see" & use all 2.5... I know Linux can and does.
I run Belarc Advisor on all my PCs. Belarc reports 2.5GHz memory. I don't think you will quite the performance increase you look to get though. The 1.8" hard drive slows down the D420... I work around that by using Puppy Linux 4.3.1 Puppy boots off a USB flash drive and loads entirely into and runs from RAM memory, meaning it never reads or writes the hard drive. I got a dramatic speed increase from running Puppy. However, the display refresh rate and the video display chipset still results in rather slow Internet performance.
Overall, you get an ultra small and light regular laptop that clearly out performs any netbook even when you have only 512MB memory and a slow side display.