Windows 7: Will Windows 7, 64-bit HOG RAM?

I like your logic! So why don't I simply add another 4GBs of RAM and call it a day.

Again, my current Dell, with 2GBs of RAM, a slower dual core Intel processor, and integrated graphics doesn't complain -- with smaller CAD and Sketchup files. I will have to run my existing CAD and graphics in the 32-bit mode (virtual XP machine) -- which is why I will use the Windows 7 professional -- or I must upgrade the to the 64-bit versions of the programs. IF I run them in the 32-bit mode, I cannot see how I'd have an issue. If I upgrade the programs and use large files, I'll likely have to graduate to a fast, independent graphics card and 4 more GBs of RAM.

Sure...you just may find that you don't use anywhere near all of it. I have 2 boxes with 8GB of RAM each...and unless I am running 3+ Virtual Machines concurrently I never come close to maxing out the machine.

Most people seem huge increases from 1 to 2GB. A small increase from 2 to 4GB and almost nothing going from 4GB to 8GB.

If you want to keep the graphics card option open, you might want to opt for a 500 Watt PSU rather than 400 Watts. Just to be on the safe side.

The less strain you have on the PSU, the better. If you go by the old bridge builders rule, the safety factor is 3x the required.

PS: what pparks says makes a lot of sense.

Note that with PSU's that's not necessarily true. PSU's become less efficient at lower and higher power draws than their rating. Most quality PSU's have about an 80% efficiency at their base rating, and that efficiency drops when pulling more or less than that load. A good rule of thumb is to size your system to draw about 60% of your PSU's continuous power rating.

Of course you don't need 3 times - I was just joking. Your 60% rule seems reasonable but I was not aware of it. I just wing it and then a bit more beef is safer.