Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

This is about to change. I would wait about a month, LR 6 is about to be released.

https://blogs.adobe.com/lightroomjournal/2015/01/update-on-os-support-for-next-version-of-lightroom.html

Your system will need to have this as a minimum.

In order to leverage the latest operating system features and technologies, Lightroom 6 will require Mac OS X 10.8 or above, or a 64 bit version of Windows 7, 8 or 8.1.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

If you are getting a desktop (more bang for the buck), you will either save a lot of $$ or get a more powerful system if you consider a Windows system. For your budget of $2500 you can get fast i7 quad core cpu 32 gb ram, dual 30 bit 24" displays, workstation graphics card that will show 30 bit color when editing in Photoshop (if you go that route), and more internal storage than any Apple product can offer. With any motherboard that supports Intel Rapid Storage technology, you can use a small inexpensive SSD drive to cache a 1 TB system drive, (90% of the performance of an SSD only solution, but only 25% of the price), and 3TB storage drive (possibly larger in this budget), and you can use high quality high duty cycle enterprise drives as opposed to the junk you by from Best Buy. Something to consider. BTW, I have been specifying and building machines since 1983. I also have supported Apple products.

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

What software do you currently use?

There are some excellent suggestions here - and I would add Phlearn and anything by Russell Brown - a senior creative director at Adobe.

Do not consider images that come out of LR as finished. They may be close, but you still need a pixel editor like Photoshop to take a great image and perfect it.

dbeals Loc: Washington State

Where can I buy a system like the one you have described? iMac with 3.5GHZ Quad-core i7 with 16mg memory, 1tb serial ATA Drive @7200 with NVIDIA Geforce GTX 780m 4GH GDDR5 will cost me 2,513.00 with 27" monitor.
I've been looking at Dell and iMac. But Mac is expensive but is high quality from my research.

lightcatcher Loc: Farmington, NM (4 corners)

You can try http://www.jncs.com/php/bundles1150.php?gclid=CJXg487fk78CFabm7AodxzkA7Q

Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

You can't do that system with a Mac. But if you are genuinely interested in a PC, I will take a few minutes and spec one out for you. Send me a PM.

BTW, the GTX 780 with 4gb memory is a wonderful card for video, but you are paying for features and memory that you don't need for Lightroom an/or Photoshop. And 16 gb ram is "entry" level for PS, but more than adequate for LR.

Working with both platforms, there is nothing "premium" about Mac. Inside they are pretty much the same, with one notable exception if you are doing Photoshop - the Mac OS does NOT support 30 bit display, only 24. Mac fans will say that it is not necessary, but until you've edited in PS on a 30 bit display, you will never appreciate the difference in accuracy and gamut that such a display system provides. It's easy to do that on a PC.