I have the Xonar D2 and it does not have front port capabilities. As Kougar said, the DX has them:
It is PCI-E 1X to so it can go in one of those empty slots.
I cannot think of a better card with front panel connectors.
Intel E6300/Nouctua NH-9U w/dual 92mm Panaflos
XFX 680i LT
Patriot PC2-6400 2X2GB LL
2 X BFG 8800GTX in SLI
Enermax Revolution 620W PSU
ASUS 24X DVD/Seagate 250GB SATA 2/THermaltake A90/Windows 7 Ultimate 64