As supplied, the PC can only connect to a router via an Ethernet cable. (That's normal with desktops anyway). If you want to connect it via Wi-fi, you'd need to add a suitable adapter. (A PCI adapter, which needs to added internally, costs £16.99 from the same firm. A USB adapter would cost about twice as much).
There are plenty of desktop units around for £300 so dont feel limited to this one.
It is Ok, but nothing special.
I notice it has Windows 7 Professional on it, which is normally used by people in business. While this is not a problem you are payng more for it so it may be better to find one with Windows 7 Home Premium on it.
Here is a Dell for about the same money, with a better CPU on it
I have bought a Monitor from Misco in the past and the service was excellent.
At the moment I am waiting for a delivery this week of a new base unit from Ebuyer,com. You could try them and see what they have?????