A PC running Ubuntu Linux 10.04 since it works, and uses less RAM, and CPU power then most other operating systems I tried, and It has enough software like Opera, Chrome, Gimp, OpenOffice, Audacity, etc which is compatible for Ubuntu for me to use.
Toshiba laptops aren't very good because they overheat so easily, but like alfred said, make sure to have a cooling pad in that case. I don't think it's very fun either.
I generally don't like HP, and use Dell instead. I prefer Dell particularly when ordering servers for my company. But honestly, all things put on the table, I care about the specs and price most. Dell is my favorite because it has a good amount of customization available without needing to be hassled over the phone, IM, etc., with its configuration page being simply a webpage for most if not everything.
My PC is an HP though because mom bought it for me awhile back. It's good but mom's HP didn't last very long and mine also breaks relatively frequently.
I have to that with my Acer laptop that thing gets so hot when reading cds that it cuts off. Well it used to I fixed the problem but it still gets scorching hot 😡
Windows 7 Pro 64-bit on two home built desktops (my Dad builds)
Main PC Spec > Asus Maximus Extreme motherboard X38, IntelQ6600, Cooler Master V8 CPU Cooler, 8gb Corsair DDR3 1333MHz, ATI Radeon HD 5670, Corsair Force 60 and 120 GB SSDs , Sony DVD/RW SATA ReWriter (Black), Corsair Obsidian 800d Computer Case (Black)