You’ve got a couple of options about how to do this best.
First of all the basics. Your 8mm tapes are almost certainly analog and you need to get them into digital format.
Assuming you have something to play these back on (the cam-corder they were filmed on) you could get a basic video capture device, hook it up and encode them to MPEG-2 (thats the digital format that DVDs use).
Pinnacle are a well known brand that make capture devices. Generally they are USB and seem to work quite well. Follow this link to see the sort of device you are after.
If you have a newer video camera that has a firewire or USB2 output, such as some of the DV or mini-DV types (generally the higher end models) then you can actually hook your 8mm player to the input of your DV and connect your DV camera to your PC (normally via firewire or less likely through USB2). You can then use pretty much any video application - including Windows Movie Maker which is free with XP - to capture into digital format on your PC.
If you follow the second method, you will probably end up with DV-AVI format video. Your video application should allow you to convert this into MPEG-2. Nero comes with a tool to do this, as will most full-featured DVD burning software.
Another option as you mention is buying a DVD recorder. Quality wise you aren’t going to find very much difference unless you start spending serious money. 8mm is a reasonable source format and you probably won’t have issues such as poor sync or colour bleeding. The overriding factor in the quality will probably be when you configure the encoding rate. This determines how much video you get on a disk. Low encoding rates = lots of video at lesser quality. High encoding = close to source quality but shorter length.
8mm video is effectively a lower resolution than DVD (240 lines for 8mm, around 480 lines for NTSC DVD) so an 8mm video frame contains a lot less data than a NTSC DVD video frame. Bear this in mind if you go the DVD recorder route - there is certainly no need to record at full quality.
Of course, if you don’t have the equipment, you might not want to buy it just to convert a few tapes. In which case pretty any much video bureau will convert for you. There is one slight caveat here. 8mm video is normally in one of 2 formats. Plain 8mm or a higher quality called hi-8. The tape may be marked (but this isn’t 100% because you can use a hi-8 tape in a 8mm recorder ;-(. The video bureau should be able to figure this out and let you know.
Basically, you should tell them you have n 8mm tapes which you need encoding into MPEG-2 with straight Dolby Stereo. You should be able to have the tapes encoded either into a mastered DVD (which is basically a DVD image that you can burn straight to disc, slot into your DVD and play away) or delivered as MPEG-2 files - the same as those you might download from the Internet.
Personally, if you have an interest in this sort of thing and a reasonable spec PC (e.g. bought in the past 3-4 years), I’d shell $80 or so on a capture device and do it yourself. Once you’ve got the settings as you like them you can just push play and let it do it’s thing.
Tim