Accel gen 7 serial cable or USB converter

[suprspooky]

Hello, New Forum user here, seems like several folks have set up the Accel Gen 7 DFI.
I need some input based on your personal experience with the Laptop to ECU comm. cable.
The used setup I purchased came with the older Serial (RS-232 DB-9) cable but no Key.
I see Keys are available for purchase, either the old style Parallel Port Key or the newer USB key.
Which route should I take, I have Laptops with Serial/Parallel available with 1+Ghz CPU so I can do either.
I've read posts that say the older cable is better (less comm. problems). I'm assuming I'd need the DB-9 plugged into a USB to Serial adapter and the USB Key to use my old Cable.
Will the USB type Key allow me to plug directly into DB-9 Serial Port?
I more interested in solid Comm. than cost.

Oh and the project is a SBC to be converted to Hilborn 8 stack efi, replacing a Holley 4Bbl/Edelbrock Scorpion setup, 18ft Jetboat (capable of slight lateral g's). I bought the Hilborn setup used and it included the Accel DFI.

If anyone thinks there's a better forum for me use, let me know. I've read quite a few posts here and it seems like plenty of info that will port into my project.

Thanks,

Dave