I agree with Tboy...
...more details are needed.
Every time I left a company I was offered a package. In most cases I negotiated something better.
The 1 week per month guideline Tboy gave is a good one - I've never received less than that, and frequently negotiated more. In one instances I was with the company a year...and negotiated a eight month package...but only after being paid to negotiate for 2+ months. n another instances I was given 2 months after being on board for a little over three months...plus i was given the signing bonus I negotiated in the original offer.
One of the things you will want to ask for is outplacement assistance - even if you never plan to go back to work. Often these consultants can help with retirement planning. Ask for a very robust package...at minimum one that last for the same "period" as your severance (even if you take lump sum).
Speaking of which, I'd be careful about taking a lump sum...the tax implications are ENORMOUS. You can negotiate that your pension payments and other pension benefits begin immediately. You can also negotiate that your termination be handled in such away that your EI can begin ASAP (it all comes down to the terminology used for the financial consideration you are given. If you do not call it salary...then you are eligable for EI right away. People...usually higher management...negotiate to have their pension plans altered to reflect a severance all the time...more years added, higher base salary calculation, etc.).
I would also ask for job skills training to either be provided by the company via direct payment to a 3rd party, or that they cover the cost of training to research and secure on your own. I have received that in a severance package as well.
Final suggestion....if you are here then you know how to use the internet. Research, research, research. Research until you are blue in the face, so that you can discover what other things to ask for. Determine what it is you want, then talk to a GOOD lawyer (most are hacks, who will just piss off your employer). Do not be afraid to spend 1500 - 2000 dollars on just a couple hours of good advice from a TOP NOTCH law firm...if I read you correctly, you are talking about a package possibly worth a few hundred thousand dollars, so be smart. Discuss with your lawyer if their negotiating on your behalf would be better....it has pros and cons (pros...company knows you mean business...con...things are no longer "friendly") so you will have to really give this some thought. In either event though you want to TALK to a lawyer so you know your rights, and so that you can say "my lawyer thinks", even if they never become engaged.