For desktop computers at work, I have previously bought Dell Precision workstations, then we bought a couple of Dimensions which have worked fine with most things bit slow with photoshop but they are getting on abit now.
I like to be able to work from home as well as work, so bought a Dell Precision laptop a few years ago in fact have 2 of them M90's, which have been great and problem free. Then a couple of years ago I saw Lenovo launched their ultimate workstations W700, they were really expensive, over $4000 I think(nothing I wanted to try and afford ), anyway I bought one that was one year old, at a great price, with 2 year business warranty left.
Its got Intel Extreme processor, 8GB memory, 1gb graphics card it had 2 500gb 7200 harddrives running as raid 0, but I changed that put a 300gb SSD in and kept a 500gb 7200 drive for for files etc, have always taken an extra monitor in a montitor case with me, so like all computers at work, I use it as a dual monitor set up, which makes life so much easier. I love being able to work on one screen and watch video tutorials, or work from customer artwork, or google for information, or use the other screen as a tool dock, find it really hard to work otherwise these days.
They dont make the 17" at the moment which is a shame, but it certainly doesnt feel dated in any way, rates really high on windows experience about 7 which is pretty good. I bought mine from an IBM tech, and ordered an extra power supply from Lenovo and it came next day with UPS, so they work well servicewise, like Dell.