Well, it doesn't matter what your current GPU is, the problem is that your OS isn't enough. Minimum for GTA V is 64-bit Windows 7 SP1/8/8.1 (or Windows Vista SP2 if you have an nVidia GPU).
So, the absolute minimum you will need to do to even launch GTA V, let alone play at any resolution at any kind of quality setting, is upgrade to 64-bit Windows 7. I would also highly recommend upgrading to at least 8GB of RAM, if for no other reason than to assure good overall system performance (& because 4GB is the minimum for GTA V, 8GB is recommended).
Beyond that, your CPU is above minimum. The big question is what your current GPU is, and at what resolution you will be playing. With your CPU, I doubt you're currently gaming any higher than 1080p (& even that might be stretching it), so you don't need a GTX 970 (or an AMD R9 290/290X). Given the recommended GPUs & your current CPU, a better & cheaper buy would be something like the R9 270/270X (they're slightly faster rebranded HD 7870s, & they're currently between $150 & 200 a pop). As an alternative, if you can swing it you might consider getting the GTX 750Ti & upgrading your CPU to a FX-6300 -- that, of course, will depend on if your board is an AM3+ & if it can support the CPU. And before anyone weighs in, the FX-6300 is better than his current CPU, it's solidly between the minimum & recommended AMD CPUs, & using it instead of going to an Intel build means he doesn't have to reinstall his OS just to try & play GTA V.