Wireless and wired on separate subnets for incr. security?

I am trying to add wireless connectivity to my network. My current setup is Toshiba Cable Modem -> Wired Router (Linksys BEFSX41) -> Gigabit switch (SMC something) -> PC, XBOX, NAS (soon). I bought a netgear MP101 to play my mp3’s while working in the garage and I came across a d-link wireless router DI-524 that was free after rebate. My thinking was that I would add another level of security to my network by putting the wireless on a different subnet than my wired devices and controlling access to the wired network through the firewall in the Dlink. So basically I would be connecting the D-link router to the output from the Linksys router. The problem is that the PC that will be serving the mp3s will be on a different subnet from the wireless device. After hours of trying to get the setup configured yesterday, I am still unable to access the configuration page of the D-link while my PC is connected to the Linksys.

I read through the FAQ’s on wireless networking on this site and I read in one of them that windows cannot share files across subnets. So is this whole attempt at adding a layer of security a futile one? Am I better off making my life easier and using an access point? Does anyone have suggestions on how to configure my setup? Does anyone have any experience setting up this router to be used as an access point?