Remember that I said that Windows Vista is pretty? Yes it was. Just like Windows XP was before it became XP from Codename Whistler. I don't get why Microsoft does this always. Granted that it is not as ugly as the every so popular blue Luna (yuk!), but still. Just look at it.

Look at what the basic used to look like and what it looks like now (via LonghornBlogs.com). Apparently their reason for changing was that there is too much grey. Not to mention that Aero is only available to people with a version beyond Windows Vista Basic and with a good graphics card. I guess they really wanted to move away from the grey as Mac OS X is just so huge on it.
On a better note, however, the new build 5472 is apparently faster and they finally fixed the problems with video playback. Some even say that it works better with the new nVidia drivers and that some games are actually running at reasonable speeds again.
It seems like you’re an expert at themes and other customizations in Windows. I’m wondering whether themes will slow down my Windows XP. I usually turn every feature off except for smooth fonts. I’m afraid that turning any visual feature on will affect my computer’s performance. I know for sure that a wallpaper slows down the computer. Thus, I don’t use wallpapers like I used to.
If you are visual styles service running in the background already, then there is no difference. However, if you don’t then you will notice it slow down. Are you talking about your Athlon XP machine or the Athlon 64 machine? In neither I saw a perfomance hit big enough that I couldn’t live with it.