Okay.....I'll take a stab.
I assume that both computers are able to access the Internet at the same time. So, the only problem would be linking the two PCs together, right?
I did some researching (I know very little of the Mac world)
Here's what I found....
1- It is more likely your brain will implode before you ever get a viable network between PC and Mac without software.
2- If you enjoy using your brain, I found a cheap piece of software that will do all the configuration and allow you to transfer files.
http://www.crystalfiresw.com/products/Wormhole.html
If your desperate for printer sharing Miramar Systems makes a program called PC MACLAN. It's fancy; it does all the work for you; and it runs about $150.
I can't vouch for wormhole, but PC MACLAN works great. It's used at the University where I intern and they assure me it's stellar
I'm sorry I can't help out more with your problem, but maybe a big Mac head will see this and enlighten us all.
Good Luck