Recently I've just been recording acoustic guitar with a USB mic, but want to start recording properly with my electric i.e. not just into my shitty sound card.

I've been looking into the Line 6 KB37 for a while, as it seems to be everything I need..in one.

MIDI controller/USB interface/Mixer etc etc and comes with software and VSTs. If I got that then I'd just need SuperiorDrummer or something and I'd be away.
However I just came across some information that most of the Line 6 series, including the KB37, don't support Windows 7 drivers yet So I don't want to waste money if it won't work for me.

Do you guys know of anything similar, or a similar cost effective way of getting the same methods to record?

TL;DR: Looking for an inexpensive USB interface and MIDI controller (mainly to program drums) that works on Windows 7 drivers.
Try for a firewire interface (M-Audio are a good brand for that kind of stuff), you may pay for a little more but it beats the bad latency that some of those Line 6 USB interfaces have. I should know as I have had 2 different POD's in the past and the latency (latency being the time it takes for the sound to reach your ears from when you first hit a note or what not on your guitar) ruined it for me.
i don't know about you but i have used 5 interfaces very extensively and the Line 6 UX2 has less lag than the 2 m-audio interfaces i have used a ton. To be honest between UX2, Fast Track Pro, Saffire 6, and Lexicon Lambda. There is no real difference in latency its mainly just volume and noise from pre-amps that separates them.

I have only used one firewire and that was a few years ago and it didn't have any noticeable differences from the USB. Until you start recording multipltracks (such as 4 or more) I don't think there is a huge difference between USB and FireWire unless you have a low end computer.
Obviously as you said it does depend on the models but I have used the UX1 in the past and found it very laggy even with the ASIO 4 ALL. As I work in IT as my profession I have always had a good pc.

I am also currently undergoing the official Pro Tools courseware and from what I can see fire wire is 400mbps and USB 2 is 480mbps however due to the architecture of both firewire is still faster (due to being peer to peer as apposed to master slave) in the real world by up to 70% in some cases. I don't know about USB 3 as I haven't seen a whole stack of USB 3 devices as yet. I am only going from personal experience of the Line 6 devices. I have never had bad latency and have all gotten great quality from M-Audio.