What do I need in a computer?

I'm looking for a desktop computer I do mostly web browsing, listening to music and dowlading it, word processing and I do some photography. I don't play much games unless it Face book games. I use a Lenovo ThinkCentre at work and love it so I want too look at one of those but I don't know what I need in it how fast of a processor, how much ram, discrete or dedicated graphics? I want something that will not slow down while multi tasking or doing whatever I need to do on it. I want to spend about 1000 or less and it needs to last about 3-5 years

As far as being fast, get 2 hard drives. One SSD (120GB should be enough) and a big mechanical hard drive. Put your OS on the SSD and as many programs as you want. SSDs are super fast so that will be good for multitasking. Then use the mechanical HDD to hold music, movies, ect.

Since you are accustom to your employer's Lenovo Think Centre. Find out what components are in it and investigate how much it cost? This will give you a starting point. Acer & Alienware are other great products.

You are looking for nothing more than a:

Core i3 Processor
4GB RAM
1TB Hard Drive

That would cost you around $500 and there will always room for upgrades.

For future proofing your PC you can't really do that anymore unless you pay ALOT now then in 4 years it will be pretty mediocre.

Use high configuration desktop to satisfy your needs like should have good capacity hard disk, ram, fast processor etc. Use some latest PC software which will help you to keep the system faster.