No, not DOS games, some older Win95 stuff that doesn't get along with Windows 7 x64 too well. Trust me, I've looked into every common solution for these problems, solved them for some games, but there just aren't any fixes for the few the remain. The most irritating one at the moment, since I want to play through it again now that I've got the expansion, is Tiberian Sun. It runs awfully on modern hardware, and the only "solution" is to disable hardware acceleration for DirectDraw, which results in a blank screen on some hardware, mine included. The game's utterly unplayable once you have more than a handful of units on the screen at once, due to constant framerate fluctuations.
Another one, the Win95 version of SimCity 2000, crashes any time you attempt to save. For now I'm playing the DOS version, but that's capped at 640x480, Win95 can run at your desktop resolution. (I've also heard SimCity 3000 craps out on multi-core processors, but I haven't tried that one myself, never liked it as much as 2K or 4.) I could probably get away with using XP for them, but I'd rather go 98, some of these games already had minor issues on XP.