I have not looked at the latest mice from logitech (had a Mx518 and loved it) but a few months ago I got the death adder by Razer and it is a very high quality gaming mouse for around 60 dollars.
The Logitech G15 to me is just plain awesome. It is around 80-100 dollars though. It is good if you play at night without lights on because it has LED lights that light up the keys.
No idea what the "professional" gamers use but when I play I want the best equipment and that seems to be a real good combo right now.
# Hyperesponse™ gaming keytop with fully interchangeable keys
# Headphone-out and microphone-in jacks
# Media center keys
# Two USB ports
# Gold-plated USB connector
# Razer Battledock™ for add-on accessories
# Approximate size: 522mm (length) x 220mm (width) x 33mm (height)
Made for gamers, by gamers. Best keyboard I've ever used. I haven't used many, but from the specs and performance I've gotten out of this baby, it's golden. I'm not a Razer fan, but the reviews and look of this keyboard got me to buy it, especially since it was made by gamers.
Here's 3Dgameman's review on it:
It's what made me buy it.
Razer has released a new keyboard which is sexy, and probably better than mine. You can check the razer site for that one. The only drawback is that all the keys are lit up (you can turn them off too though), and I hate that. But to each it's own.
I've used quite a few mice for gaming. I've gone from a Microsoft ball mouse, to a Japanese name branded (I forgot the company name ) laser mouse, to another Microsoft mouse, but this time optical, to a Mx518 (horrible mouse IMO), to finally a Razer Deathaddder. Not only is the feel great, but the performance outclasses any mouse I've ever used. It's only made for right handed players though, so if you're left handed and use your mouse with your left hand, it wont suit your needs.
Here's the specs:
* 1800dpi Razer Precision™ 3G infrared sensor
* Ergonomic right-handed design
* 1000Hz Ultrapolling™ / 1ms response
* Five independently programmable Hyperesponse™ buttons
* On-The-Fly Sensitivity™ adjustment
* Always-On™ mode
* Ultra-large non-slip buttons
* 16-bit ultra-wide data path
* 6400 frames per second (5.8 megapixels per second)
* 60–120 inches per second and 15g of acceleration
* Zero-acoustic Ultraslick™ Teflon feet
* Gold-plated USB connector
* Seven-foot, lightweight, non-tangle cord
* Approximate size: 128mm (length) x 70mm (width) x 42.5mm (height)
Most of our members and the entire gaming community worldwide use this mouse. It's precision is like no other, and its shape is unique. A lot of members have upgraded to the Lachesis, which is similar to the Deathadder, but it's ambidextrous and has the capability of 4000dpi compared to the 1800dpi the deathadder has to offer.
I also have a SteelSeries 5L mousepad, which is huge, soft, and it doesn't cause any skipping or lagging when moving my mouse in the slightest way possible.
Well, there you have it. I'm not telling you to buy these products and to forget about everything else, just telling you what you asked for.. and got really specific about it
Anyway, good luck in hunting for your PC accessories, and I hope you make the right choices.
CS:S admin. PM DennyCrane for assistance. 
) laser mouse, to another Microsoft mouse, but this time optical, to a Mx518 (horrible mouse IMO), to finally a Razer Deathaddder. Not only is the feel great, but the performance outclasses any mouse I've ever used. It's only made for right handed players though, so if you're left handed and use your mouse with your left hand, it wont suit your needs. 
