i bought laptop acer aspire 5535 with ati raddeon hd 3200 graphics card. it has also 4gb ram. craphic card has got 256mb memory and it is written that it can be up to 1408mb graphics memory. then how to add or i have to buy it ?? also is there any way i can change my video card??

Your integrated graphics chips has 256MB of dedicated memory. This RAM is in addition to the 4096MB of System RAM. You can select to share System memory (RAM). The amount you can share is dependent on the amount of installed RAM. Your integrated graphics MAY already be sharing 256MB of System RAM. You need to boot into the BIOS (setup) screens at start up to access those settings. Setting the amount beyond a certain level is not productive. Keep in mind that when you allocate RAM for the graphics it no longer is available for use as System RAM. You can experiment a little to find the sweet spot but you may already be there. Right click on My Computer and select properties. The general tab will show the amount of RAM available. Subtract that from 4096MB, which is your total amount of RAM. That will show you how much System RAM is currently being dedicated to Graphics. That number would be added to the 256 of dedicated graphics RAM for the total amount.

"craphic card has got 256mb memory and it is written that it can be up to 1408mb graphics memory. then how to add or i have to buy it ??" Your graphics uses "hypermemory" meaning that the memory amount will change depending on graphics load. If you're just surfing the web, you certainly don't need 1408MB graphics memory so the system will just use 256MB. Besides, the 1152MB difference in memory (1408 - 256) is "stolen" from the system memory, so rather than having roughly 3.5GB to run Windows, you'd only have access to about 2.4GB. And I think you got that 1408 number wrong...I just googled up your laptop info & it says "ATI Radeon™ HD 3200 Graphics with up to 2048 MB of HyperMemory™ (256 MB of dedicated)" so that would mean the graphics could steal up to 1792MB from the system. "also is there any way i can change my video card??" No, the graphics is integrated into the motherboard & is not upgradeable. If the HD3200 isn't sufficient for your needs, you'll have to buy a different laptop with better graphics.

oh no.. i went in bios menu and i only could choose 64, 125 and 256mb but the max should be 2048 MB.. what to do??

"the max should be 2048 MB.. what to do??" I just explained it...what it is that you don't understand? The onboard video has 256MB of it's own dedicated memory, but it can "borrow" more memory from your 4GB of system memory as it needs it. The technology used for borrowing is called "Hypermemory" & it kicks in automatically...there's nothing you need to do. And just so you know, it doesn't stay at 2048MB, it constantly borrows & returns memory based on the graphics load. Why would you want 2GB (2048MB) of graphics memory anyway? 256MB should be enough for most uses, including gaming. The HD3200 isn't all that great for gaming anyway, regardless of how much memory it has. It's considered a Class 3 card (1 being best, 5 being worst) & it ranks 98th out of 170 notebook graphics tested: http://www.notebookcheck.net/Mobile... As stated in the following link, "older games like Doom 3 or Quake 4 should be barly playable": http://www.notebookcheck.net/ATI-Ra... Which would you prefer...4GB system RAM w/256MB video, or 2.3GB system RAM w/2GB video? Most people ask how to disable Hypermemory so that there is no sharing of the system RAM.