For Vista, look at the MS requirements…and double it at least and make sure it's certified. Triple if you can afford…then Vista should rock your socks. If you learn how to use it, Vista features and technology blows XP away…when it works. ;) You want it to last so get 64-bit Vista Home Premium or Ultimate.
But if you have old programs, they might not work (esp. with 64-bit version). Vista compatibility list wiki here:
http://www.iexbeta.com/wiki/index.php/Windows_Vista_Software_Compatibility_List
You have to know a bit about computers to get them to work (for those old programs that have problems and IF there is a solution. Internet has a lot of solutions that smart people share).
Ultimate is the best but if you don’t think you need anything that fancy, Home Premium is good too. Get a good video card if you want to Aero graphics (at least 256MB 128-bit in the newer cards). Better if you can afford.
Recent release of Service Pack 1 made things better and more compatible with hardware. Unfortunately, Microsoft marketing made people think it will work with old computers but it’s very risky so that’s why there are so many problems. It’s too far ahead in technology and requires new hardware and too many manufacturers sell cheap computers that don’t run Vista good.
Vista uses extra RAM to store commonly used files in a new activity known as “disk caching”. The computer determines which files will be accessed most and copies it to RAM (where it is much faster than accessing your hard disk). This includes components of the programs you use on a regular basis. When you need more RAM for programs you launch, etc. the computer purges the “least likely used” files from RAM to make room. That’s why if you look at the performance monitor, Vista always has near zero “free” RAM. So in theory, the more RAM (for disk cache) you have, the faster your computer will operate.
Vista Home Premium and Ultimate has Media Center, where with a TV card/USB adapter (if not integrated) of the type that fits your TV, acts similar to an advanced TiVo. You can play your videos, schedule recordings, etc. As an added bonus, you can get a wireless keyboard / mouse or gyro-mouse and it will be sort of like remote control.
Deals of America and Tech Bargains catch good deals on HP and Dell’s and sometimes you can get like $500 off!
http://www.dealsofamerica.com/
http://www.techbargains.com/
Unless you are an artist, most Universities (and programs) as well as the rest of the world use Windows. WinMacs are popular (of the 7% of Mac users…5 of 7 are WinMac’ers).
http://marketshare.hitslink.com/report.aspx?qprid=11
But for the price, Macs don’t run Windows as well as other brands.
Macs are durable because many have an accelerometer in there that can "increase the chance" of saving your hard drive when you drop it. Like those used in airbags. The power cord is also magnetically attached so it reduces the chance that you yank it off the table.
OSXMacs can exclusively install Final Cut Pro (which is good for media work). Adobe CS is also good and available for Windows but works better on a OSX. The Windows version actually looks like an OSX port.
Most Mac users eventually use Windows on it however. (of the 7% of Mac users…5 out of 7 are WinMac’ers)
http://marketshare.hitslink.com/report.aspx?qprid=11
I would suspect that many OSX keepers are artists as usual. Emotion workers are generally not as good with computers as logic workers so OSX's are good for them.
Windows runs better on windows machines of course, but sometimes it doesn't really matter that much to most users.
Mac Pros:
OSX stability
OSX is easy to use
Dual-bootable to Windows
More durable than many brands
Trendy
Mac Cons:
Not as much peripheral support
Not as much software support
Windows doesn’t run as good
Expensive
Minority: currently Only 7% use Macs [2% OSX, 5% WinMac] (91% use Windows)
PC Pros:
More customizable
More choices
More styles
Cheap hardware
Vista has best gaming capability (DX10)
PC Cons:
Less stable (unless you are an IT pro)
Many are relatively not as fashionable
Not as user-friendly
Some extra features in Windows requires advanced knowledge to use
The extra features require better hardware despite your use of them or not
Details of features can be found here:
http://en.wikipedia.org/wiki/Windows_Vista
http://en.wikipedia.org/wiki/Mac_OS_X