What three things would you consider most important for selecting a unit that would run fast?

With a computer if that is what you are talking about?

If so, you should look for these three things although it varies on how you will use it, (hacker, photographer, music, artist, gamer, casual user, seeder, etc.) Then you need to ask PC or Mac? Each have pros and cons accordingly. Here are the top three things I look for in a computer.

1. Processor.

Intel is a good company for processors and the new i5 chip is fine for nearly anyone. 2-3 ghz is usually high standard and is fast enough for any use usually. This also works great if you are a casual user.

2. RAM

4gb of ddr3 is always enough. Ram is the hard drives backup in some cases. if you are running low and the drive can swap for ram memory. I don't study RAM too too much, but read up about it to learn more.

3. Graphics card.

Graphics cards arnt necessarily for gaming, they are for everything the internet has to offer such as videos, photos, games, rich media, etc. The computer I recently bought has seperate memory for the graphics card specifically...well for graphics processing.

PS. Also get a large enough hard drive for your files that are both existing and that you will receive, download, upload, create in the future. But keep in mind that if a computer says it has 500gb of hard drive space, it is really about 450gb because of the programs and settings and all the things that make a computer run already on it.

Also, this is pretty obvious, stay with Windows 7, or mac os x 10.7.1 lion if you go that way in order to keep you as up to date as possible.

also, buy antivirus protection, norton or mcafee are few great brands. this will ensure your computers speed for a longer period of time.

even more, when using the internet, you shouldn't use internet explorer which is preloaded onto every pc or even safari that is on every mac. the fastest browser out there is google chrome. extremely fast speeds, it automatically updates necessary software, and half you page isn't taken up by those pesky toolbars.

last thing, make sure the computer has plenty of ports. usb, vga, hdmi, ethernet,etc. and the battery life is also always a big factor.

if i can make a suggestion if you are making plans on a laptop. if you are a casual user/intermediate expert, i recommend the laptop i just purchased recently. The Gateway NV53A. Webcam, ports galore, and all of the great features i just talked about, were based around this computer. If you are looking for desktop, i don't know to much, just make sure the processor is fast, it has at least 4gb of RAM, it has a good graphics card, plenty of memory(-40 or 50gb in most cases), and the impact on your wallet is not to bad.