Can I rip a DVD with a CD-ROM drive?

No! CD-ROMs have another physical structure than DVDs which makes it unreadable to standard CD lasers. 

Can't open input file 'whatever' or 'too many secrets' in VobDec

I'd really like to get the latter error message some time - reminds me of Sneakers, a really great flick. These messages basically mean that you have not read my instructions and/or the readme for VobDec carefully. There you could've read that you have to authenticate your DVD drive first - just insert a disk and start up the player, that's all. You have to repeat this procedure as soon as you've opened your DVD drive again - doesn't matter whether you insert the same movie again or not or as soon as you reboot.

You'll get this error either when you're ripping from the DVD directly and forgot to authenticate the drive or if you've corrupt VOB files. In the latter case you'll have to rerip the VOBs, preferably using Vstrip directly. 

Delete DeCSS and DODSrip immediately and use VobDec. That program has been around for more several month now and I can't possibly understand why there's still people that haven't even heard of VobDec.

Make sure that you've turned on DMA on your DVD drive. This settings can be found in Control Panel - System - Device Manager - CD/DVD Drives. Then right click on the DVD drive and select properties and you'll find it. In Windows2000 it's in Control Panel - System - Hardware - Device Manager - IDE ATA/ATAPI Controller - Primary / Secondary IDE-Channel. Also, the latest Toshiba DVD drive - SD-M1512 - can only rip at 2x speed when the DVD is scrambled (most are). There's no workaround for that problem. If you think your drive is too slow you can also try to connect it differently, some drives like to be secondary master, some don't like the secondary bus at all, etc.

It's a command line based tool, you can't just double click on it.