I'm running 3640, 2505 and 2501 routers in my home lab, with three 2924 switches. Are the 2924s too old, and would you recommend the 2950 instead?

Jim, the 2924s are old enough so that the command syntax differs from what you're likely to see on the exam. That said, Cisco de-emphasizes switch command syntax, instead asking you to interpret output more than worry about command syntax. Given the used process for 2950s, if you have $300 to spend, I think it's worth it to buy one 2950 with the standard image. If you're working with $100-150, make do with the 2924s.

What do you think about Cisco 1603 as main router for CCNA Lab?

I haven't looked too hard at the 1601 in the past, but my recollection is (take this with a grain of salt) that it'll do most everything you want for CCNA in a router. I think you'll miss a few items covered beyond either 12.3 or 12.4 IOS (mainline) - go to www.cisco.com/go/fn to look for such stuff with the feature navigator. From a price point perspective, I think the 2600s tend to be similarly priced today with maybe a little better longevity - but my memory's fuzzy there.

What are the typical things that users do wrong when creating home labs?

I think they don't stop to consider what kinds of things they'll do with it once they get it. If the goal is a free-play space, the combination and number of devices is less important. If the goal is to use lab exercises from a class, book, Web site, etc, then that ought to drive the process.

How important is having L3 switches in a home lab for CCNP?

It's my opinion, but for CCNP, it's not worth the money in a home lab. If you're going for the CCIE soon after, it probably is. Here's why: you can do most everything except the Layer 3 config with a 2950 with the standard image even. If you really want to configure it, you can get a switching Network Module for your inexpensive 3640, and the config (supposedly) is the same. I'd spend my money on 2950's today, or 2960's when the used price drops, and more routers, rather than an L3 switch.

I have only covered CCNA 1 and 2. How should I approach CCNA 3 and 4?

Well, you've got me there - that's more oriented towards the Network Academy - at least I think so from your question. In the past, 3 and 4 don't always equal the 2nd CCNA exam (ICND2 these days).

I am relatively new to the network admin field having some experience and I was wondering what is a nominal timeline for someone studying for the CCNA and having say 3-4 hours a day to commit to studying?

It of course depends on from where you start. If you know nothing about any of the topics, and it's all self study, I'd guess it at about 150-200 hours of study. However, even if you know a third of it already, you could reduce it to 100 or less. That's a pretty general plus/minus 50 per cent number, though.

Can you recommend a CCNP online course vendor and a CCNP bootcamp vendor?

www.skyline-ats.com. OK, end of commercial! Seriously, I'm affiliated with a learning partner (Skyline-ATS), so I can't be unbiased. The Cisco Web site lists all the learning partners. CCNP classes probably run regularly in the top 20-25 sized cities in the US.