Tom, raisins are grapes, and grapes add a vinuos quality to wine that
no other fruit matches. But raisins can affect the flavor, although
that is largely a function of which lind of raisin you use.

For peach wine, you would obviously want to use a white or golden
raisin. These are usually made from Thompson Seedless Grapes, which
are fairly neutral in flavor. You could also just use crushed fresh
Thompsons in the wine. If you can find them, try Sultanas, the
raisins of muscat grapes. They offer a nice flavor enhancement to
peach.

Finally, you can try adding a white grape concentrate.

For raisins, use anywhere from one-half to one pound per gallon of
wine -- the lower number is sufficient for body improvement. For
grapes, use no more than two pounds per gallon. For grape
concentrate, use 11 ounces per gallon.

Jack Keller, The WInemaking Home Page
http://winemaking.jackkeller.net/