I agree with Wheel Man.
However - you won't be able to play lightgun games - and emulation is not quite the same as hardware. It's close, but not quite the same. Even 100% emulation still passes through alternate i/o. I have just about every emulator and rom you can think of. (I've got over 2TB of HD space) I have picked up USB to Console controller adapters and they work good, but you still will run into the occasional snag. However, there are advantages to emulators such as being able to pause at any time, save and restore rom states at any time. You can even do good old game genie type hex address hacking if you want.
I wish I had never sold the following systems: Intellivision, Atari, Colecovision, NES, Sega Master System, Genesis, Turbo Grafix-16, Neo Geo Gold (modded), Saturn.
I have held onto the following since: Neo Geo Pocket Color, Nintendo 64, Dreamcast, Xbox (2 both modded), PS2, GamePark 32, GBA, NDS, PSP.
Strangely enough an Odyssey2 system found it's way into my hands. This and Intellivison were the first game systems I had as a kid. The unit doesn't work, but I hold onto it for sentimental reasons.
If you want to collect games - it's pretty simple - don't toss them out. When you aren't using them - pack them up with bubbletape in cardboard boxes and toss them up in the closet. Eventually when I get a house - or a larger apartment, I'll move onto collecting Jamma Cabinets. There are some killer deals on ebay for those. I've also been looking at picking up a Supergun unit. Google for that if you aren't familiar.