You can get a wifi/bluetooth adapter that install via PCIe slot such of these.  Just remember to connect the included cable to an internal USB port for bluetooth to work.   If you prefer Dell OEM, just look for Dell part 07HP8W.  A picture is attached for reference. [IMAGE]Dell 07HP8W
Hi, once again! I have lots of questions so you may be seeing a lot more of me in here. It's probably 15 years since I did anything like this so I'm a bit lost and need a little help and a few pointers. I'd like to install wifi/bluetooth and I'm not sure what I should buy? I mean are all the PCIe cards compatible? or am I looking for something specific?  All help is much appreciated!! many thanks in advance! 
Installing wifi/bluetooth in T3620