I updated my DSi via internet and had the same problem. You'll have to buy a newer R4 card because the bios in the DSi now recognizes the old card and blocks it. You can sell or give your old card to someone who hasn't updated their bios. Get the newest firmware for the new card to be able to the latest rom releases.
Replacing the optical drive in a laptop usually consists of removing 1 screw on the bottom side of the case. This screw may have a embossed picture beside it on the case indicating it. Look for a screw that is about 6" directly behind the door of the drive. Once the screw is removed the drive can be pulled by hand from the PC. You will have to use the plastic door cover from your old drive on the new drive. Most just snap off and on but it could require removing a couple screws also. This is one of the easier repairs you can do yourself to a laptop. The drive will have its part number on the outside of it. You can get a replacement from Toshiba or possibly through ebay or an online source.
Isn't the MC760 VMU a cellular modem? They usually have software on the modem you can access and install to your PC to connect to the internet through Virgin Mobile on a pay as you go basis. You don't use your router that is connected to your broadband service. For this you need a wi-fi card. Update: I don't think you can change the SSID on the usb modem. You might consider the MIFI option Virgin Mobile offers. Try this link: http://www.virginmobileusa.com/mobile-broadband/mifi-2200.html?intcmp=p-hp-pt3-bb2g-122010 .