Well, it's actually pretty moot, as systems with more than 4GB but less than 8GB are uncommon:

- some of the newest Intel CPUs/chipsets have triple-channel memory controllers, so you see configurations of those systems with 6GB, 12GB etc.

- some systems support different-sized memory modules at the same time. For example, some laptops come with 3GB RAM, i.e. 1x 2GB + 1x 1GB. This is not really recommended, as RAM is so cheap (get 2x 2GB instead), and by having different-sized modules you can't take advantage of dual-channel RAM or other similar enhancements. Also, I haven't heard of any systems that support different-sized modules above 4GB

These days, a lot of systems have plenty of CPU, a lot of the time they're disk-bound. If you're working with large data sets or otherwise hitting the disk a lot, having extra RAM to use as cache can help a lot. Where you start to see the benefit, probably depends on your workload.

Another way to address disk bottlenecks is with a SSD. I think Rick Strahl mentioned recently he's been getting good results with one.

>Thanks Al. My laptop is currently running 32-bit XP Pro and I have 4 gig of RAM and I knew it wasn't all quite being used as RAM (about 3.5 gig). However, what I was really questioning was Craig's statement that there's not much gain in using 64-bit until you have twice as much RAM (8gig vs 4gig). I doubt if the reasons you stated below for using 64-bit on a 4 gig machine would hold up for much more than 4 gig ... certainly well before you hit 8 gig, no?
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>~~Bonnie
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>>>>You're in business if you have the hardware to support it. I asked about 32 vs. 64 bit when Win7 RTMed. From what I could find, it appears you don't really get any gain with 64 bit until you hit 8 Gig RAM.
>>>
>>>Please correct me if I'm wrong, but I thought you needed a 64 bit OS to be able to access more than 4 gig of RAM?
>>
>>That's true. However, you can install a 64-bit OS with only 4GB RAM (or even less). WRT exactly 4GB RAM, this was discussed at a couple of Win7-related events I went to recently, the takeaways were:
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>>- 64-bit can use the full 4GB, 32-bit has to leave some address space for memory-mapped hardware, typically can use only 3.5 - 3.6GB, sometimes less. IOW you gain a little useable RAM
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>>- 64-bit software tends to be larger - 64 bit pointers etc. so it takes away some of the gain you get above
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>>- some 64-bit CPU instructions are more efficient than 32-bit equivalents
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>>- a lot of real-world, commonly-used software is 32-bit only (e.g. MS Office), so users tend to spend significant time thunking in WoW64, which offsets gains in other areas
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>>So, 64-bit on exactly 4GB seems a bit of a wash.