Installing external DVD-RW makes computer perform incredibly slowly

Hi, we have a Dell Dimension 2350 (I think that's the model, it's a 2300 series), 2.2 ghZ P4, 512 MB of RAM. I recently added an external Lite-On DVD-RW drive, that is connected into one of the back USB ports. I love the drive, I went with the external rather than the internal because we're probably going to get a new computer pretty soon, that I hope will be equipped with an internal drive, in which case I'll pass this drive along to my wife whose Dell laptop only has a CD/DVD-ROM, no burner.

FYI, the computer is also equipped with a DVD-ROM and a CD-RW drive, both internal, came from Dell that way.

The thing is, since installing the external drive, it has slowed down the overall performance of our computer tremendously. It has slowed down Internet surfing worst of all. We are still on a dial-up connection, will be going DSL or cable shortly since those things are now available to us, but with the "accelerator" from our ISP (EarthLink) we've always gotten respectable dial-up Internet performance. Now it has slowed to an absolute crawl where it takes forever to load a page.

I know that this drive was responsible. When we installed it, it started showing up in our system tray as a USB storage device, with the little green icon. I finally had enough and went through the "safely remove hardware" spiel, which means the drive no longer shows up in My Computer even though it's still hooked up. And since then, the computer performance has picked up to where it was. Although I will toss this out, a while back we purchased one of those Canon three-in-one (scanner, copier, printer) units and hooked it into one of the USB ports as well, and as long as it's on ... and showing up as a USB storage device as well (it has memory card slots, for what that's worth) ... our computer was running slightly slower than it did before, but not as dramatically as when we hooked up this external drive.

Can anyone give me any idea of what's going on here? Are there some USB conflicts? My understanding is that all those USB ports are 2.0. Are there any settings that might need to be adjusted (I tossed this out on another non-Dell board and was told I might need to go into Device Manager and make sure things are going to different ports, although the responder didn't really give me good directions at how to do that)? Could this be a RAM issue? Are both of these units such resource eaters to where we're asking the computer to do too much and need a gig of RAM?

Thanks in advance for any help!