The S10-3t basic model comes with the SIM Slot ready and also has the empty PCIe for the wireless card to be put in. If you see it also includes the antenna’s ready to put your 3G modem. I upgraded the RAM to 2GB since I had that lying around from a previous Netbook that I had. This seems to help quite a bit for multiple applications open and two web browsers open with at least 3 to 5 tabs open in each browser.
Here you can see that the SIM card is inserted into the SIM slot and is not covered by Lenovo to block it. I do believe that the BIOS might be locked down to certain PCIe modems that you could use.
Here is the SIM Card Slot without the SIM Card.
So it seems that even if you buy the basic model with the Starter Edition you still have the SIM Card slot to use, of course you still would need to get the 3G modem. I connect the S10-3t to my BlackBerry Storm II with BT DUN and is working good. I have upgraded to Win 7 Ultimate Edition on this one.