big icons only for dektop?

you can´t.

you have to use a program for that. plenty of ways possible. you could buy DesktopX or maybe WindowFX.

HoverDesk 3.0 will be released soon and can also do this.

you can also run LiteStep on top of Explorer.

or you can use the SharpE desktop.

interesting is also to use a metering tool as Samurize or Rainmeter for that. both support PNG and actions on clicks on defined areas. as they are metering tools you could also display a progress bar for the drive size near the drive icons for example.

....

more help than you wanted

have to add that LiteStep, SharpE, Samurize and Rainmeter are free.

DesktopX 2.0's IconX function will do this quite nicely for you....but it's still beta on ObjectDesktop and it tends to rearrange your icons on you. Stardock's aware of this and working on it. Expect it to be fixed before the final release.

WinFX's "Show large icons on desktop" option is "problematic." It will display large icons. However, it also tends to forget where you put them. So if you like your icons arranged a certain way on your desktop you get to reposition them alot. Just before WinFX 2.0 came out, it was posted to the newsgroups that no new code to address this would be written before the 2.0 release.

And as IconX is really a lot nicer than the WinFX function, I can't say as I blame them (anymore).

An omission on my part: Not everyone experiences the icon rearrangement. Some of us did, but you may not. You should try WinFX 2.0 or the beta of DesktopX before you assume that it wont' work for you.