First, you need to realize how transactions are spread through the network. When you start your monero node, you usually connect to a maximum of 16 nodes by default (there are currently about 1000 nodes according to a quick google). When you send a transaction, what you are doing is sending it to all your connected nodes. Then, these nodes will propagate it to their connected nodes and so on, till the whole network has received your transaction.
But ONLY the first 16 nodes you personally send your transaction to know your real IP. When they in turn propagate your transaction, their connected nodes wont see your IP, but their IP.
Thus, the only way for an attacker to reliably connect your IP address with a particular transaction is by controlling most of the nodes in the network to increase their chances that they are one of the nodes you directly connect to. Then they check which IP has sent the transaction the earliest, which is most likely the creator of the transaction.
And even if they do control a statistically significant portion of the nodes, unless it is close to 100% they can't be absolutely sure.

That is the "massive" resources.

But even if they do that, all they can connect then is a transaction hash to an IP. No addresses - stealth addresses take care of that. So it's not really useful for much.

As for the TOR stuff, you can run the normal tor client locally and run monero through that just fine. On linux I use torsocks which makes it trivial, I'm sure there are similar alternatives for windows.