Vista is actually pretty light on ram usage according to math
Honestly, Vista's requirements aren't very high at all when you do the math. The biggest "bloat" Windows ever faced was Windows 2000, where "usable" ram requirements went from 32mb to 192mb in order to run a usable box, that's 6x more in less than 2yrs!!! Where as a usable Vista setup is 768, which is only 3x that of XP's 256mb ram and the jump took 5yrs!!!
Minimum requirements are garbage... XP CANNOT run efficiently at 128mb of ram. Heck a default boot is around 110mb or so, you need to heavily customize XP to get the bootup smaller, which is something that 99% of users don't know how to do.
For an end user you need 256mb in order just to run your everyday apps at the same time; IE, Office, anti virus and a music player. When you get into a family setup with multiple logins running (aka user switching) you're needs skyrocket to 768mb or more. And if you are a developer (SQL server, Visual Studio) you better be rocking 2gb or more.
Finally, I also believe we won't see the larger benefits of the Vista improvements until Windows 2009 (yes it's slated for a 2yr release date) where there will be a reworked UI and more improvements. Heck we might even see some benefits in Vista R2 that's suppose to come out in about a year. So obviously I'm not on the "Vista is the best thing ever" train, but I do realize it lays a lot of groundwork for vast improvements. Even one of Vista Aero's project managers said (I lost the url) that Vista's UI is like invention of fire. In itself it's kind of cool but it will take awhile before the truly amazing stuff to come out, the example he list was the combustion engine.
Finally we need software in order to push hardware. I'm a firm believer that RAM isn't any cheaper today that it was in 2001 because software requirements have halted since XP came out (ok Office XP and then 2007 did want more ram). You need demand in order to push production. We're on the wave of a bunch of great technology innovations; Intel's Core 2 Duo gives massive amounts of speed with a small watt/heat footprint. NVIDIA is coming out with $70, $100, $130 DirectX10 based cards and even Intel has an onboard chipset that can do DX10 too. Finally memory companies are ramping up to 80nm and 65nm based memory, which will bring prices down, especially in the area of 2GB ram chips, which are still very overpriced. Finally 64bit computing puts us past the 4GB ram limits we've been having and Vista supports this very well and Intel & AMD have been pushing for awhile.
Yes, right now as we stand Vista may seem a bit needy, but in only 3-6 months from now we'll see some huge improvements in memory and video, especially when you look at prices.
PS: Stop whining, Vista is not an OS to stick on your current Win2000/XP box, it's a new OS for new boxes. Just like how Win2000/XP cannot run on the same box as your98/ME setup, the requirements have simply changed. Upgrade and grow up, or keep using XP. Nothing is new here, MS has always been on a 2 step OS plan. A first OS comes out (95, 2000, Vista) and it usually requires a new box to run efficiently because of massive improvements. Then a 2nd stage OS comes (98, XP, Win2009) out fairly quickly that will work on your same hardware.