The Optiplex GX520 Mini tower has two PCI slots and one PCIe x1 slot. The small form factor and ultra small form factor versions have no PCIe slots at all. Thus the only GX520 that has any hope of doing any decent gaming at all is the mini tower, but PCIe x1 cards are limited to the low end. You could get creative by carefully cutting out the end of the PCIe slot to plug in an x16 card to run as a x1 but the old CPU and being limited to a max of 4 gig PC2-3200 makes that not worth it. Yes, despite what Dell says, a GX520 can take 4 gig, if you get two of the right 2 gig sticks. With a PCI ATSC tuner card and a PCIe x1 GPU with HDMI a GX520 could be turned into a cheap DVR. If you can find one real cheap, a GX620 board will drop right in and you'll get 4 DIMM slots (still limited to 4 gig), a PCIe x16 slot and two more SATA ports so you can swap out the IDE optical drive for a SATA one - heck, go for two, or install another SATA drive in the floppy bay. Going even crazier, if you want to do some metal work,...
CDMA phones in europe and asia are available with RUIM or removable user identity modules. Same as SIM cards but different software loaded. There are phones available there with 2, 3, or 4, possibly even 5 card slots with 1 or 2 of them for CDMA. Verizon and Sprint don't want that in north america. It's about control and mone, not preventing fraud or other such bs.
Samsung and Micron/MicronPC/MPC laptops had fingerprint readers and security software using them since the late 1990's. Dunno if Samsung continued to do so after MPC went out of business in 2008, cutting off that channel for selling Samsung's high end laptops in the North American market.