Rumour has it that Westvleteren 12 will be available in Ireland in January and in all honesty I don't think it is that different to St Bernardus 12 - both are great beers if you are in that part of the world. But, despite having spent a week in Westvleteren last September (when the brewery was closed <!-- s:| --><img src="{SMILIES_PATH}/icon_neutral.gif" alt="

" title="Neutral" /><!-- s:| --> ) there is way more to Belgian beer than Westvleteren. However, if you are in the area make sure you pass by Oostvleteren on a Saturday when the DeStruisse brewers can be found (with the aid of Google) selling such fine beers as Pannepot to the general public.
I would strongly agree with the person who said to pick up a copy of Tim Webb's book but I would caution that it is [b:1rkq5x11]very[/b:1rkq5x11] selective in the beer bars it recommends. Frankly, you don't need a bar to have a list of 150 beers if all of the beers it has are great - and it happens. We visited a bar in Veurne that wasn't in the book that had Petrus Aged Pale - sublime. As another example the Wit Paard (sp?) in Oostvleteren wasn't in the book but it had some great beers (e.g. Quinitine - fantastically hoppy strong Wallonian ale)
Having said that the book is a fantastic resource in terms of discriminating between the crap and the great breweries. The main thing with bars is to skip on the bars with the Primus branding as their "abbey" beers are rubbish.
As for Brugges, it is definitely worth a visit, and The Little Bruges Bear[/url:1rkq5x11] is well worth a visit, not least for the delicious DeKonnick, but don't be a sucker - don't stock up on beers to bring home in the town. I saw Saison Dupont that retailed for 2.50 in the Ardennes going for 7 or 8 euro in off-licenses in Brugges.
For me though, the biggest highlight of our trip (apart from the Popperinge hop festival) was the Drei Fontanein restaurant and brewery in Beersel just outside Bruxelles. The food was great and cask faro, kriek and lambic was a delicious treat - not to mention the privilege of forking my cash out to Armand DeBelder[/url:1rkq5x11] himself when we made off with a load of fantastic lambic and geuze.
Big regrets were not trying Taras Boulba or the other De la Senne beers and not stocking up on De Ranke. (If only my taps poured XX Bitter!)
The other practical caution is that if you are planning on using trains Bruxelles might be a good base, as other places may not have good connections.
Keep an eye out as well for some of the other unsung heroes of the Belgian brewing scene such as Kerkom/Bink of Limburg province or La Rulles from the Ardennes whose beers seem to be little hyped in the US (feel free to contradict me here Biertourist or others in the know) but are straightforwardly amazing brews.
But the main thing is to remember that, a bit like the UK there is so much great beer in Belgium that you will find it even with a blindfold on!