Another vote for the Lenovo Thinkpad/T-series. Having worked in IT and run a private computer service, nothing in the Wintel world stands up better or lasts longer (without going into a purpose-built hard-use machine like the Panasonic Toughbook). They're in the same league as Apple as far as the build quality and longevity goes, not to mention spare parts are available long after production ends since they're very popular with corporate users (due to their durability).

Dell tends to get a lot of praise from people who don't have to service them. They're not well built, they don't perform well, they don't last as long as their competition, and the hardware is often inferior or "dumbed down" out of the box. You'll pay more money for a lesser machine.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]