I have a dell 435t from a couple of years old. i7 bloomfield 920 radion hd 5870. thinking about getting a 660ti. should i start a new build or is my 920 ok for now with that gpu. going to use for gaming and htpc
The Radeon HD7950 is a GREAT choice. It's the best GPU you can purchase at the ~$300 price point at the moment due to it's MASSIVE performance potential once overclocked. It performs great at stock settings as well.
And I don't have a personal preference I've used a GTX560 Ti and a Radeon HD6870. I've had driver issues with both solutions and generally I'm pleased with both Nvidia and AMD/ATI.
For me, it comes down to who has the better price/performance at a given price point. And at the ~$300 price point, AMD just happens to have that crown at the moment
I've had both in the past (Nvidia vs. AMD) and both have their issues and advantages but atm I would consider AMD to be ruling this gen of graphics cards. I own 2 7950s in CF (both OCd) and they kick ass even for my Eyefinity setup.
Of course you don't need 2 if your just gaming on one monitor
I would bother upgrading the CPU until 2015 when Intel releases Skylake.
I believe Haswell is just going to have a relatively small performance increase over Ivy Bridge when it is released next year. The primary improvement will be in reduced power consumption most notably for laptop and table versions of that CPU.
Broadwell is going to be released in 2014 and it should have a good performance increase compared to Haswell. But it is the last of the socket 1150 CPU series. Skylake will require a new socket in 2015.