People will slam you for not searching this because it has been answered, sort of, a gazillion times. Problem is the answers are spread out amongst 2000xl and 2000classics and everyone else's specific needs.
What I learnt was:
1 You can get an external SCSI card reader if you like. hooks up like your ZIP. Simple to do but a little hard to find. I got hooked on the idea of the card reader being INSIDE the machine so I left this idea behind.
2 The 2000classic doesn't have an internal SCSI cable or a connector for IDE drives. The XL does so adding one to the XL is relatively easy.
3 Forat(link) will do a mod that lets you put a Card reader in your Classic for about $300 (...barely remembering...) including the drive. You have to just ship it to them. They answer emails fairly quickly and you are usually talking to somone who actually does the work and knows what they're talking about.
4 Someone (MPC3000 maybe... search it) on here did the mod themselves. Probably only worth looking into if you have any experience with a soldering iron
5 Someone will eventually send you tothis page which has tons of info about card readers and MPCs but it mostly refers to XLs
Thas' all for now
good luck
Slick
PS
I scored a deal on an XL so I have a VST card reader kit on order and I have a Classic waiting for a new NV slider and then Ebay.