Hello, i got an ms dos laptop. It is possible to provram arduino uno via serial, and to compile the code on ms dos or windows 95/98?
No. [u]This Page[/u] tells you what you need.
Programming of the Arduino (or ATmega chip) could (theoretically) be done with anything, but the Arduino compiler/IDE has certain constraints/requirements. It is open source so it you are really good programmer with lots of extra time you could port it to a different system.
If that's your only computer perhaps it's time to upgrade! 
Put Linux on the laptop.
Ditch the Murkysoft junk.
I recently donated a laptop I had from the mid-1990s. It had Windows 98 when I got it (it probably originally came with Windows 95). It maxed out at 160 MB of RAM. I immediately installed FreeBSD and, later, Linux on it.
Anyway, I doubt you could get any Arduino software running on Windows 98, let alone MS DOS, but it's possible under Linux. At the very least you could get avrdude and avr-gcc working, if not the full Arduino IDE. That's what I would do in your situation.
What on earth are people doing trying to make things work on two-decade old laptops? I can't give away windows XP or even early win7 laptops for free! (I have a stack of three of them which I will never use, and the one person who expressed interest decided against it because he had too many laptops of similar vintage sitting around already and couldn't justify the space another one would take up).
Just raid the e-waste trailer at the local dump - Win7 laptops are now outnumbering vista/xp ones is the waste stream. There's a trick you can do with stickykeys and a recovery mode boot on Win7 to remove the password, so you don't even need to reinstall the OS (though usually you'll want to, as the general public is very good at making an absolute mess out of their home computers)
I had a preety good pc, but when I am on the go, I cannot program an arduino, and I don't know where to get an pc, for verry cheap.