what is the best OS?

Well.....it's tricky. In fact, I think all depends on the use you are planning for this box. There are some issues to consider, for example, How literate are you on this theme? Do you have enough time to investigate? For example: If you Install Vista, or maybe XP if you can get a license, you can be operative in an hour or two, thinking of Windows and Microsoft Office. Normally, you need a printer, you put the disk driver in the cd reader, and .. you are in the business. At a price. and with all the concerns about viruses, malware, etc. OK. let's talk about linux. Price? almost 0... read carefully.. almost. But what flavor of Linux? ... again, it depends on the use you are planning for the box. Assuming you take a decision, .. good luck. I hope the distro you choose works fine on your hardware, that you can get the correct drivers for your peripherals, .. that .. that... Linux can be a good choice (people is talking a lot about Ubuntu, you can give it a shot without installing, so ... why not?), but there is a lot of things that can fail, so the time you reserve for installing and refining can be between a couple of hours and ... a couple of months. Good luck.

shifting to linux can be tricky as not all motherboard drivers are made for linux, linux is an excellent network OS but to make full use of linux, one should have a working knowledge of command line interface ie know certain commands, i have been using windows xp sp3 for last three months n i can bet this is the best microsoft have come up with, it has fixed 99% issues with win xp OS, vista is heavily loaded OS and unnecessary takes lot of processor and memory resources. u can try win xp sp3, it has the look n feel of vista but takes only 200 MB of RAM. take care.....

I'm currently using windows XP SP2. I have installed Vista but I downgraded it back to Windows XP because of of many hardware and software issues. I will wait for Vista to become more stable just what I did in XP. in terms of security Linux is the best OS for me. for GUI the mac os is the best. but in terms of user friendliness Microsoft OS's is the best.

I am firmly in the Linux camp and although setting up can be a bit of a fiddle sometimes, many times it is not, and most distos have very good support forums, who can normally offer a fix if you need it. Why not download some different Live Distros of Linux, burn them to a CD and test drive them first before installing them. If you are still not sure, you could also place both operating systems on your PC, and have a dual boot setup from the beginning, or I believe you should also be able to run linux within Virtual Machine. Hope this helps.

i would go with windows XP ... i will need to format miney computer in couple days and will go with windows XP, if i decide, maybe i will add and some service pack, maybe just the 2, becouse i have only that one

I like to recommend windows XP. It's the most solid OS of Windows ever. Vista is just in a new state right now and has a lot of bugs. Linux, for me, is not a good choice. It has huge compatibility issues since some devices attached to your system may or may not have Linux drivers.