I am also having issues with getting SoundFonts to work, on my new Windows 7 system. Here is my setup:
CPU: AMD FX 8150
Chipset: AMD 990X/SB950
Sound Card: SB X-Fi Titanium HD
OS: Windows 7 Ultimate 64-Bit
MIDI software: AnvilStudio
Here's what happens: Everything *seems* to work okay, Soundfonts load, no errors, etc. But when I try to play a MIDI file in AnvilStudio, it plays way below the correct tempo, and it seems to be having trouble playing more than a couple of voices simultaneously, as random voices keep getting dropped. (I can post a sound sample if that helps give you an idea.) Then, if I try to just play individual notes on the keyboard in Soundfont Bank Manager, it will play the first note I hit, then go silent until I either change the Instrument or restart SFBM. If I try to play MIDI in any other app (e.g. Windows Media Player) it just ignores the Soundfonts altogether and uses the Windows default voices.
Does anyone have any idea how I might fix this? I'll continue to use my old Windows XP system just for MIDI if I have to, but I'd rather get it to work on the new one...