Originally Posted by oimi
So, what is the alternative? Obviously I am not going to go and buy an N64 in NTSC format as that would require me buying everything again.
Aside from what Jo suggested, there really isn't one.
As for PC cards to run the image through.....Any card that can do this to a good standard will not be cheap. In fact, I am fairly sure it would be more money than a xrgb2+ type device.
Quite simply, there are plenty of cards that can take a composite signal from your N64 into your PC, but the ADC (Analogue to Digital Converter) these include will often render the image worse than it would be by plugging it into your screen directly.
Buying a card thats got a good (ie. production quality) ADC on board, and can do decent filtering is big money. So much so, you probably won't find them at the majority of computer retailers, its not your usual run of the mill equipment.
Having said all that, your simply missing the underlying issue. No matter how you connect an old console up its going to have to scale the image at some point to the resolution of your screen. Even if you had digital directly from the console it would still happen. The console outputs a lower resolution than you want and you cant change this.
Honestly, there is no easy solution to this. If there was, everyone would be using it.