Since I worked both in PC and Mac for my jobs, perhaps I can shed some light on this subject.
Your files on the PC shouldn't have too much issue being read on the Mac. Jpgs, Tifs, Targas, Gifs, BMPs, and all those other image formats should work just as well on the Mac with no modifications required. You may have to install a third party program such as Photoshop or Illustrator if you wanted to view or edit some of the more complex image formats such as Targa, Ai, Eps, PSD, PDF, etc. But overall they should open just fine on a Mac.
Your text documents may have a bit more trouble depending on the program used and format saved. If you used Microsoft Office for most of those files, then you should be ok. However some other files, such as ones made from Word Perfect, etc. may have issues opening up on the Mac text programs. The solution to this is to just purchase Microsoft Office for your Mac (They made it)
Now another concern you may come accross is if you make files on your mac, save them on your mac, and then try and send those files to a PC. Macs have the tendancy to create files with no file extensions (ie: setup.exe will just be setup on a PC when copied) So when you copy a file over to a PC, make sure that you rename the file on the PC with the added extension, or else the PC isn't going to know what the heck it is.
As it goes for general comparisons between PC's and Macs, well that depends on what you want and/or like.
PC's can and will crash or get all mucked up in time, but I have always found that there were various solutions available to solve the problem on the fly, and I have yet to loose any major files on a PC. However when I worked on macs, esspecially during the time I was in a photography studio, the Mac crashed an awful lot (Something to do with the RAM and the Video Card having issues with one another or something)
When a Mac crashes, it crashes bad. I believe the new OS has added a little thing similar to Windows' Task Manager so you can shut things down on the fly as well which give you issues, but from memory, I didn't like it still. Usually when a Mac crashes, you're screwed, you have to restart the computer and hope it doesn't happen again, with no explinations.
Macs don't have to deal with anti-virus programs, because they don't get viruses (yet) mainly due to most of them being designed for PCs, rather then Macs. So Macs are good in that aspect.
However, PC's have more programs available on the market in comparison to the Macs, and overall, if you see something being advertised on TV, be that a program, game, movie, whatever... chances are it'll be on a PC before it's on a Mac.
Macs are apparently better for graphical use in comparison to PC's as their graphics are intergrated into the system, but I personally never noticed a major difference between the two for what I need to do.
It basically boils down to how you build your computer and what you put into it. But then that also comes down to cost differences. While Macs are becoming more closer to the price range of Dells, Compaqs, IBMs, and the sort of brand name PCs, if one was so inclined, usually you can build a custom PC yourself, or by a nearby computer store for far less then the brand name computers, or a Mac, and possibly more powerful too.
With Macs, there's not much for customizing, besides upgrading RAM, CPU, Video Card, etc.... but then you get into costs again, esspecially when you may have to get the parts shipped to you, or you ship your computer to them if you do not have a store nearby which specializes in Macs.
Overall as an unbiased opinion, both Macs and PCs have their pros and cons.... and depending on the system you compare to, there's not really much any difference for performance. It's mostly all about preference.
One thing though.... if you haven't been on a Mac before and only experienced PCs, although both Operating Systems seem similar in operation, they are still very different in many aspects and you will basically need to relearn a whole new OS and how it works.
Personally and professionally though, I prefer PC's over Macs. My reasons are that I find I can do more within the Windows OS then in the Mac OS, they are generally cheaper the way I build my systems and use them, I don't like how limited the Mac OS is when a problem occurs, and I don't choose my system based on it's outside apperance. I have lost many files on a Mac during crashes, while I have only lost a select few over the years on a PC.
