There is problem with old MSDOS games, so DOS box is solution. Also I got small list of problems with TV Tuners and drivers, but now I hope all vendors have 64bit drivers. For Media Center I use ffdshow 64bit Alpha, it work great, but I got 1-4 crashes per year. For Media Player it possible use some codecs as for 32bit system. Visual Studio 6 (+Windows Tabs) and 2005 plus Visual Assist working fine. For VStudio 6 I found guide how to install it, and for me it works. Office 2007 working fine. Some games have 64bit versions (Half Life 2, Crysis,...) but 32bit games also work without issue. My vote for 64 bit system, as it allow use 8Gb for me - so I can start VMs without any performance lags for host and guest OSes.