I use a Samsung SSD (Corsair P256). It works great. Maybe not quite as fast as the Intels in some areas, but it is faster than the X25 in others. I went with the Samsung because I wanted the 256GB storage at a better cost vs. the more expensive Intels with less storage.
If you go to an Apple authorized 3rd party repair shop (usually a local computer store) they can most likely do the installation for you. And so long as it is done at an authorized shop installation will be covered by warranty. However, usually for a shop to do such a repair, they will likely require you to buy the drive through them, and they will probably charge a much higher price than what you could get if you bought it online, plus the labor cost of having it installed. They will probably charge you at least MSRP for the drive, and likely $50 or more for the install labor, more if you have them install the OS onto the disk. If you later experience problems with the drive though you should be able to get it serviced under warranty via that shop.
If you do it yourself, the computer is still under warranty but the drive is not. If the drive fails on you later on you have to take it out and have the manufacturer fix it under warranty. But if later on the CD drive stops working (or some other unrelated problem), you can take your computer to Apple and get it fixed under warranty. I did the install of my SSD myself and there were no problems (cause it's dead easy). Then my CD drive stopped reading recently and I took it to the Apple retail store. I did not need to replace the original hard drive back in nor did they give me a hard time about the self-install (i.e. blaming the faulty CD drive on a botched HD swap). If you do it correctly it will be obvious if you screwed something up like slipped up with the screwdriver and gouged out the motherboard or something.
I guess if you're really paranoid about it you could take photos of the installation to prove there was no damage done by you during the install. I didn't go this far but I did take a photo of the SSD so I had a record of the serial number in case I ever needed it without having to open the computer up again.
Just my experience.
Ruahrc