Which model of the card is it? From what I could find, it seems to be a 9400GT. If that is the case, then you won't be able to run the games mentioned. Fable 3 requires at least a GTS250. As for GTA 4, it requires a pretty decent graphics card. I tried running GTA San Andreas with it and managed to run it on lowest settings, and that too with a lot of lag!
The 9400GT (if that is indeed your card) is a very weak graphics card and definitely not one meant for/ fit for gaming. You really should consider changing your GPU (Graphics card).
Earlier, a decent switch from a 9400 was the GTS250. Today, you have multiple options in different price ranges. If you're keen on upgrading, let us know your budget and also post your complete computer specifications (CPU, Motherboard, RAM, Power Supply, etc) and then we may be able to help you out. As of now, that card is a definite no-no!
Your CPU is an Intel® Pentium® Processor E5400 (2M Cache, 2.70 GHz, 800 MHz FSB). It has 2 cores and 2 threads. But its still a Pentium! Its a bit old for today's standards.
Your motherboard may not be that much of an issue as it supports the core 2 processor family chipsets....which means that you cane salvage the motherboard and get yourself a Core2Quad for a decent price. I remember getting myself a 2.33Ghz intel Core2Quad (I think it was a Q8200) for about Rs.4,000. You should do some research and find the prices for a quad core CPU, preferably at least 2.66 Ghz.
Basically, you should consider upgrading the following, in priority
Try looking for at least an nVidia GTX460. If that's not possible, try getting the nVidiaGTS250. I know from experience that our Indian market is an nVidia fan and does not cater much to ATI cards. Otherwise, I would have suggested the ATI5670
As stated above, consider moving up to a quad core cpu with at least a speed of 2.66 Ghz. Depends on how much you're willing to spend though.
Check the brand of your PSU! If its something like Zebronics, etc, dump it and get a good branded PSU (Antec, Corsair, Seasonic or Coolermaster). Remember, your PSU would depend on your system specs, so get that in order first. A good branded PSU is a must. People have spent tons of money on getting a high-end system but try saving money on PSU's. All it takes is a simple electric spike to blast past a cheap PSU and fry your system.
Not the biggest of your worries right now, but sooner or later consider getting 4GB of DDR3 RAM.
Let us know what you think about it. If you're in Delhi, try going to Nehru Place and getting some price quotes.
Fable 3 - No!
The minimum requirement for the graphics card is a GTS250.
GTA4 - No!
The game is poorly coded and requires a powerful CPU. Plus, a decent graphics card. You may manage running the game on the lowest of settings but it will be very slow, maybe even unplayable.