Flight Attendant, as Norm mentioned you won't be able to use your Bell phone overseas. Telus and Bell use CDMA technology, while Europe (and much of the rest of the world) use GSM technology. However, as Norm mentioned there are a few models that incorporate both formats. Those probably wouldn't be my choice as they will undoubtedly be "locked", requiring Bell customers to use a roaming plan and rates as dictated by Bell (therefore you wouldn't be able to use a Euro PAYG SIM card in them).
As I mentioned earlier, the technology will be changing in a few years and both Telus and Bell have announced plans to switch so I wouldn't purchase an expensive phone at this point. If you buy a quad-band GSM phone now, it should still be useable for at least four-five years.
The model I'm currently using is a Motorola V551 "flip" model, and it's been very reliable so far. Although the V551 has been discontinued, it's still possible to find them on E-Bay (I've found brand new 551 models on E-Bay, but these are becoming increasingly rare). I've found that it's better to buy a model that was configured for a Canadian network (Rogers, Fido) as some of the US models have specific software settings for their networks. As with anything on E-Bay, one has to be a bit careful with the vendors, but I've been fortunate so far.
I tend to prefer "flip" models rather than the "candy bar" style, but you could also look at some of the Nokia models. I'm not too familiar with Sony or Samsung models, so can't offer any advice on those.
I'll do a bit of browsing to see what other models might be available. Nokia will be introducing a new model to compete directly with the I-Phone 3G and the new Blackberry Storm, but that won't be available until next year sometime. The Storm will only available on CDMA networks initially, but I suspect a GSM model is in the works (they can't afford to ignore such a large market segment).
Good luck!