Santaga,
I probably shouldn't chime in here but couldn't resist. IMO quarter round (especially prefinished) should not be used if base has been removed. I see it as primarily a product that floor installers can use so they don't have to hassle with removing baseboard and paint touchup. Problem is with most modern basebaords by the time you add in the floor height increase due to the hardwood and then add the bulky quarter round, the poor baseboard is reduced to a paltry 2 or 3" above the quarter round.
Also, I found it a real PITA to get all of those miters tight and make the nail holes look good on prefinished stain grade. Often you have to cut numerous very small pieces which is either very difficult or dangerous - take your pick. when I do it I always get some chipping on the edges and many times you cannot avoid exposed end grain which is a real no-no in stain grade carpentry. I have seen where pros do an excellent job and I can't even see the nail holes but I'm not up to it.
When I consider both of these factors, I would never use prefinished quarter round if at all possible especially if the base is being replaced or pulled. Either no quarter/shoe or a paint grade shoe molding which is much more elegant than the bulky quarter round. After I install my base above the hardwood, I put some tape on the hardwood floor and just an eighth inch or so up the base. Then you can paint the base without worrying about getting hard to remove paint on the hardwood or cutting in like a painter with 20 years experience. Pre paint your shoe, remove tape (score with a knife if using latex) and install shoe.
Not saying you should do it my way, just giving you one alternative.
Good Luck
Edit - One other tip I have found very useful for assembling small miters etc is the use of Cyanoacrylate glue. As you may or may not know, white/yellow glue takes forever to set up, has no gap filling qualities and requires clamping. The Cyanoacrylate glue bonds in 30 secs and does not require clamping. I find it most useful when I have several small pieces to assemble. I measure very carefully and dry fit it till I get all of the lengths exact and then glue them together on the bench and install as a unit. This way I get perfect joints in fraction of the time and a lot less frustration to boot.
http://www.leevalley.com/wood/page.aspx ... 10&p=42966