no, dont buy a computer, thats the worst thing you can ever do.
build one.
atleast then you can list all what you want your computer to do, then buy those parts for it. so the finished computer is exactly what you want. and not some pre-built heap of junk.
custom built pc's are very well known for less problems, where-as if you bought a ready made one, later on you will have problem after problem.
you know exactly whats going into a custom built pc, so you know you cant go wrong.
everything you want the pc to do, such as play blu-rays, gaming, internet, full HD etc
write all this down, then buy each part at a time, or all at once if your minted, custom pc's are cheaper in the long run aswel,
for example, i built my pc and i have
Intel Core2Quad 3.60Ghz
32GB DDR2 1088mhz Dual Channel RAM
Full HD 1080p Graphics Card
1400watt PSU unit
1 - Blu-ray RW
1 - Blu-ray Player
1 - DVD -+ RW Dual Layer
1 - DVD -+ RW Dual Layer with Lightscribe
All - in - one Memory Card Reader
Bluetooth 100 meters
Wifi 200 meters
4 external E-Sata connections 3Gbs
16 USB ports - 6 are 3.0
7 Cooling Fans Ultra Silent
3 - 1TB Hard drives at 10.000rpm each and a poxy 80GB IDE - just to fill a gap in my tower lol
Windows 7 Home Premium 64Bit
Wireless Keyboard and Mouse
Remote Controlled
HD TV Tuner
all on a Samsung 46inch Full HD LED TV
and im going to add even more later this month
if you have the know how, you can tweek the full computer to your preferances, i have tweed some settings but not clocked or anything like that, and when i start my pc, it takes 1.3 seconds to load to windows. thats just an example of what you can have if you wanted, i mean you maybe want somthing less complicated, or more power etc? its totaly your choice.
((IF)) you do buy a ready made thing, make sure it comes with recovery discs! as most retailers rip you off by not suppling them with the computer, its law they HAVE to, as the version of windows there made for is the one on the computer you buy. dont let them do you over. if they say none is supplied, dont buy it. if they try and charge you extra, dont buy it. these recovery discs are free