Wifi Bandwidth Question

[Squidling]

So, hello all; quick question

I want to play TF2 with a mate, both on the same wireless internet network (my home network with terrible up/down speed and slightly inconsistent ping, usually hovering around 65)

I have my desktop and an old laptop, both of which would be connected to the same router.

Now, I'd have thought that two computers = double the strain on the router/ half speed for both, but as it's the same server and both should be receiving most of the same data back from the server will the extra computer proportionally tax the bandwidth less? 

Changing ISP isn't really an option as rural Scotland is yet to upgrade to anything other than tin cans connecting everyone, and besides this is just a passing fancy, but I'd like to know if using multiple computers connected to the same server would be possible while still allowing playable ping. 

Thanks, and have a good day/night

[Squidling]

Also, if my understanding of bandwidth being a factor in ping is flawed, please do use the most obscene language that you can think of to correct me; it's been a while since I dabbled in the gubbinations of the internet's workings