They are both "low-end" cards and not very suitable for gaming.
However, if you do not game the HD4250 is a newer card and may have features such as hardware decoding of video that the 9500 card does not.
If you want more specific help feel free to ask for it and I'll reply. I know everything there is about which card to purchase, provided I know your basic PC specs, price limit and desired usage of the card.
FYI, if you do not play video games, there is a new card for $25 which works identically for basic usage on the Internet and playing video as the most expensive card available.
There are basically few programs yet besides games that make use of graphics cards.
New versions of Internet browsers are being re-written to take advantages of the hardware that DX11 cards offer. It will take a few years for most web sites to rewrite their code.
And again, the $25 card I mentioned would work great for this.
AMD-> HD5xxx series or newer
NVidia-> GTX4xx series or newer
**Neither card you mentioned is compatible with the new code being written for web pages. They would work, but not as well. The most notable feature is most of the page, including text being loaded into the graphics cards memory and being rescaled by the graphics cards GPU.
In short, web pages optimized for DX11 run much smoother.
Here's something else to read about Power Supplies.
I would add to this that, if you ever want a Gaming graphics card, you need to also know what CPU you are using as the CPU might be a bottleneck.
Let me summarize:
1) your current cards are just fine if you are a non-gamer
2) web site are being optimized for DX11 cards but most web sites will take at least a year, maybe two to rewrite their code
3) Most video games approach maximum quality settings with a GTX560Ti which costs about $220 roughly, provided the CPU is not a bottleneck.
4) On the other hand, a $100 video card provides a much poorer gaming experience for modern games, on average.
5) Any graphics card will fit in any motherboard with a PCI-express 8x or 16x slot.
6) You need to examine the Wattage, Amperage (+12V rail), and connections of your Power Supply. For a high-end graphics card like the GTX560Ti, a 750W Corsair is a good example of a compatible PSU.
7) NCIX is the best online store to compare parts. It is both organized very well and also quite competitive for most parts.
8) Many CPU's can easily gain 15% to 25% increases if a good after-market Heatsink/Fan is installed. Even a $20 HSF significantly reduces noise both in use and in idle mode. $30 to $50 is a good range. Measure your case and motherboard and compare to the HSF to ensure no issues (hitting a motherboard heatsink or RAM). More than $50 tends to be overkill unless you have a quad-core CPU and overclock to more than 4GHz.
9) *Gaming performance is usually limited by the CPU or by the graphics card. Games will vary. A perfectly "balanced" system is one in which 50% of a persons games are limited by his CPU and 50% are limited (bottlenecked) by his graphics card.
It takes some experience to estimate what graphics card is best to take full potential of a computer, especially if it's older. I'm pretty good at that (they really need a graph which shows every CPU for up to 5 years and the latest graphic card from each AMD and NVidia which "balance" this older system.)
I installed NBA 2k12 in my PC. The first time I played it, it was very slow so I decided to update the drivers of my Graphics Card. The game became much much faster. BUT after about 10 mins BAM! BLACK SCREEN! It crashes! I dont know why I played NBA 2k11 before without problems.
Here is my PC Specs
P5 KPL AM SE Motherboard
Intel Core 2 Duo 3 GHz
2 GB RAM
Nvidia GeForce 9400 GT
Should I upgrade my Vid Card?
Also I am considering buying a new gaming PC. I would like to buy an AMD processor to AMD/ATI graphics card combo but I don't know what to buy. Please help me! I am willing to shell out $850 - $950.