Have you seen the minimum system requirements for this? Wiki has them.
For Aero Glass (The eyecandy you are seeing)
This graphics mode adds support for 3D graphics, animation and visual special effects in addition to the features offered by Aero Express.
* Intended for mainstream and high-end graphics cards.
* At least 64 MB of graphics memory, 128 MB recommended, or 256 MB for 1600x1200+.
* At least 32 bits per pixel.
* 3D hardware acceleration with capabilities equal to DirectX 9.0c.
* A memory bandwidth of 2 GB/s, and as much 8 GB/s can be supported.
* Capable of drawing ~1.5 M triangles / second, one window being ~150 triangles.
* A graphics card that uses AGP 8X or PCI Express 16X 8-lane bus.
* DirectX 9.0c
* Windows Vista Display Driver Model (WVDDM) Drivers
It is likely that such a configuration will be an average configuration by Vista's release in 2006. During Vista's early alpha testing stages, the ATI Radeon 9800 Pro and the nVidia GeForce FX 5900 were the only cards compatible with Aero Glass. Since, support has been extended to most DirectX 9 Graphics cards. At this point, the nVidia FX family and up, and ATI Radeon 9600 and up are supported.
Microsoft has not released specific details of Windows Vista's hardware requirements; however, Microsoft has released some general Windows Vista Ready PC Hardware Guidelines for those wishing to upgrade to Windows Vista and have the full Aero Glass experience.
* CPU: PC systems with a modern 32/64 bit CPU. The recommended clock speed is at least 2.4 GHz at this point.
* RAM: PC systems with 512MB of RAM or more is recommended.
* GPU: PC systems with a DirectX9 GPU that is capable of supporting Windows Vista Display Driver Model (WVDDM). NVIDIA GeForce FX 5200 or higher, ATI Radeon 9600 or higher, with at least 128 video RAM is recommended.
* Hard Drive: At least 1.5 Gigabytes, or higher, depending on the version of Windows Vista.
* A DVD-ROM might be required (Windows Vista installation package may be burned into a single DVD).
That is a lot of video ram, and a pretty fast processor to run something. Now given, I am a linux guy, and was dissapointed at the bulkiness of Tiger, Tiger will still run on systems not offering that much. The eyecandy comes at risk of the machine running slow. OS 10.2.8 is installed at school on the 400Mhz iMacs, 256megs of RAM, no problems at all. Windows XP Pro is sooo slow on my 500Mhz Thinkpad 390X with 256megs of RAM.
Sure computer software will need more to run as we get faster machines, but I won't be rushing out to buy an Operating System that won't run on my current hardware.