Search for WM6BTPAN. It's a little program for the PPC that will enable the BT network access service. Run it (needs to be run once only, however if you soft-reset you need to run it again).
From the PC, connect to the network access point service on the PPC. The connection should now succeed. If yes, you're now at the same point than with Wifi.
Now in both cases the FTP connection fails because there is no DHCP server running on either machine in your small network. So there's nothing to hand IP addresses to the machines and make sure they are both in the same logical network.
The best thing to do is to configure IP addresses manually on them.
Let's go with bluetooth first as I recommend you to use that.
On the PPC, go to Settings -> Connections -> Wi-Fi -> Network Adapters Tab.
Click On Bluetooth PAN driver. Use Specific IP address, set IP 192.168.2.1 and subnet mask 255.255.255.0.
On the PC, go to control panel, network connection, and find the bluetooth one. Right-click, properties, double click on TCP/IP. Use specific IP address, 192.168.2.2, same mask as before.
Dismiss all, connect BT network and it should be all good.
With WLAN you can do just the same but selecting Wifi adapter instead of BT PAN driver on the PPC, and the wireless connection instead of the BT one on the PC. But, as you will need to set those back to auto when you connect to your home network so that the router's DHCP server can give access to your devices (and set everything again the next time you want to make your little network again), I recommend using BT because you'll most likely never use BT networking for anything else.
Side note, don't bother with IPs in the FTP client program, you can just enter the PPC's device name (set in settings -> System -> About) and it should reach it well.