How to paste over without overwriting register

I don't like the default vim behavior of copying all text deleted with d, D, c, or C into the default register.

I've gotten around it by mapping d to "_d, c to "_c, and so on.

From my .vimrc:

"These are to cancel the default behavior of d, D, c, C
"  to put the text they delete in the default register.
"  Note that this means e.g. "ad won't copy the text into
"  register a anymore.  You have to explicitly yank it.
nnoremap d "_d
vnoremap d "_d
nnoremap D "_D
vnoremap D "_D
nnoremap c "_c
vnoremap c "_c
nnoremap C "_C
vnoremap C "_C

Use the following:

xnoremap p pgvy

this will reselect and re-yank any text that is pasted in visual mode.

Edit: in order this to work with "xp you can do:

xnoremap p pgv"@=v:register.'y'<cr>

v:register expands to the last register name used in a normal mode command.