Vostro 3550 with Switchable AMD Radeon HD3550M

Since XP is dead within six months (April 9, 2014 is its date of demise), it's a moot point. 

Sorry but you didn't understand me, I wanted to use Windows XP on this rather old notebook (Vostro 3350), which is two years old. XP at that times had more than 50% popularity, but this Vostro 3350 has unfair hard blocked BIOS which doesn't allow users to switch graphics in "Fixed mode", you cannot say XP is dead because at that times when I bought this ill-fated notebook XP had really significant popularity marks.

Why Dell released notebook without ability to swith graphics in BIOS, that could improve compatability with older Windows and Linux OS'es, I believe this is marketing turn.

ALL XP support ends on April 9, 2014 -- no more security updates or patches -- and you can expect no further driver support and an increasing number of new programs and updates that simply won't run on XP.

Whatever your reason for running XP now, it needs to be resolved soon -- XP is headed for the recycle bin.

There is no "Fixed video mode" in Vostro 3350 BIOS even after update. I wanted to use WinXP without driver problems, but with Dell Vostro 3350 I couldn't, now I hate this notebook, I had A LOT of problems using it with Windows 8. now I will never buy notebooks with switchable graphics and without Windows XP compatability label!

So Lenovo able to control switchable graphics in BIOS, but Dell doesn't? I don't really care about end-of-support for XP, I could use this notebook for my pleasure starting from it's time of buy, nobody won't compensate me my nerves, as for me this purchase was useless because of "NT6 only" binding

Some Lenovo systems do support BIOS-level switching.  So do some Dell systems.  Others - mostly the cheap, low-end consumer-grade systems (the category into which your Vostro falls) -- do not.

Whatever the popularity of XP was - or is -- the OS hasn't long to live.  After April 9, 2014, it becomes a sitting duck for attacks on the Internet.

The system is designed such that there is no hardware switch - it is all software-controlled, and neither nVidia nor AMD released drivers for anything older than Vista and 7 with hybrid support.

No one is going to pay attention to XP support after next April - the OS joins Windows 98, 2000, etc. on the scrap heap of history.

BTW, my Vostro 3350 doesn't fall to cheap, low-end segment, because it is i5-2520m which is top class i5 for that times, 8GB RAM, 500GB 7200rpm (I changed to SSD), USB 3.0, HM67. These feature set can't be at the low-end, the only low-end is HD6490 (GDDR5), but in such format (13.3) for that times there was almost nothing better

In the range of notebooks, the Vostro series (now discontinued) were largely rebadged Inspirons - they were for price-conscious small business buyers - which is why you don't MUX-based switching graphics.  For that you have to step up to the Latitude series.

Yes, this Vostro is business series notebook, so it MUST HAVE Windows XP support as well, so thanks Dell, now no Dell products in my environment!

The system supports Windows 7 and Windows 8 only - it never had (nor was it advertised to) Windows XP support.