A 2009 MacBook should be using OS X 10.5.5 (or slightly later) even if it's not been updated. An off-the-shelf USB pen drive is likely to be compatible with OS X 10.4 or later, as well as with Windows 7 onwards, so you should be able to use one without any problems. (Earlier versions of OS X required you to reformat a Windows pen drive before it could be used with an Apple device).
You'll probably need a pen drive with a fairly large capacity but a lot of the cheap ones sold by online retailers are fakes, so you need to take
great care about where you buy from. However Ryman can sell you a genuine, good quality 64 GB pen drive, either in store or online, for just £9.99. (That's amazingly good value).
https://www.ryman.co.uk/verbatim-usb-drive-64gb-pinstripe
(That's not just a random link derived from googling. I've purchased several of those pen drives myself).
Simply copying the files to the pen drive and then, after transferring the drive between computers, copying them from the drive to your PC should be all that you need to do.