Hi Fabian,
Here are the details of Tim's lens:
http://www.caudata.org/forum/cgi-bin/show.cgi?tpc=7&post=16992#POST16992
It's a very good macro lens (also rather expensive but in the SLR lens game you usually get what you pay for). If you're considering the purchase of lenses I advise you to do a lot of research. Quality varies from lens model to lens model within a manufacturer's range. Believe it or not, even Canon and Nikon make several of what can best be described as "mediocre" lenses so get a review of the lens you are thinking about. A good place for lens info is the forum at
http://www.photo.net and if you're interested in the Nikon system have a look at
http://www.nikonians.com (of which I'm a proud paying member). I don't have a corresponding link for Canon because I don't own a Canon SLR (I own a Canon digicam though, the G3, and I'm rather Canon friendly) but photo.net is mainly populated by Canon enthusiasts anyway. It's stupid but most "sensible" owners of Canon and Nikon systems exhibit a mild hatred for the other system (glad to say I'm not one of those).
For what it's worth, I've read about the 18-55 mm lens that Canon bundle with the EOS 300D (aka the Kiss and Rebel 300D depending on the part of the world in which you live) and for a bundled lens it's rather good (i.e. you pay relatively little extra for the bundle but get good value for money).
There's a lot of debate about this camera actually because many people suspect that Canon can't be making much profit on it due to the low price. This is because the sensor (the 6.3 megapixel CCD/Charge Coupled Device) costs a lot of money and it's surprisingly good.
To anyone thinking of a digital SLR I'll tell you what I would do - if I had the money and I didn't own any Nikon lenses I would already own the Canon

. I'm going to hang on for Nikon's new equivalent camera though, the D70, which is expected within the next 3-4 months and has very similar specifications.
Of course I should say that the quality of your photos is more dependent on your technique than your equipment (though nice equipment is wonderful to have), so don't expect to take photos any where near as good as Tim's when you start out. With practice, some talent and research (with perhaps a small portion of luck) I would like to think we can all aspire to approach Tim's level (at least that's what I keep telling myself

).
An important note about Digital SLRs: In case you're not aware of it, most mid and all lower end digital SLRs, such as the Canon 300D, have a focal multiplier of 1.5x. What this means is that essentially you are actually closer to your subject when you take a photo. This is because the image sensor is actually smaller than the equivalent area of film for which SLR lenses are designed. So in effect a significant area (a wide border) that you would see on film is removed in the case of digital, effectively making the photo look like you are closer to your subject. In practical terms this means that a 35 mm lens is actually a ~52 mm lens. This is nice if you like to take telephoto photos (like bird photographers do) or macro photos (like Tim and most of us here on Caudata.org) because it means the photo appears to be more magnified. However, if you like wide angle photography (such as those people who take landscape photos) you are in a difficult situation because you'll lose a lot of your wide view. The lens bundled with the Canon is rated at something like 18-55 mm, but when used with the 300D it is actually 27-~83mm. I hope that makes sense.