border crossing from Darjeeling to Nepal?

I did Kathmandu to Sikkim around November 2011, and considering Ive been travelling in India, Nepal and South America since then I must say it was the worst bus/jeep journey Ive done in all the last 8 months. Kathmandu to Kakarbhitta was 19 hours approx then quite a while to get our jeep organised which was 3 hours to Siliguri (normally 1 but traffic was terrible) then 5 hours to Sikkim by jeep (or about 3 to Darjeeling). Im not sure where you want to go in Nepal but if its straight to Kathmandu and you can afford it DO IT.
If not then get a jeep from Darjeeling to Siliguri, then a second jeep to Kakarbhitta. Then with as much patience as you have and a cushion/pillow for your behind (not joking that I was black and blue after), plenty of tolerance of people playing instruments on the bus for money and of course very loud Nepali/karaokee music, then and onlt then get on the bus.
I remember looking into Nepal to Darjeeling and thinking that this was the best land route or maybe just the one I could find most info on. Sorry I cant give you more info on bus companies, prices etc but Ive sent all my journals home. One bit of advice for Nepal though is check your Indian visa if you intend to return there. Double entry means you have one more entry into India but has to be no more than 2 months out of India. Many friends got caught with their multiple entry visa which means you can re-enter India but only after being outside for 2 months or more. Also do not overstay your visa, we did by 2 days as we were told by the immigration people on entry that a new 15 day visa can be bought for 25usd or pay a 2-3usd fine per day of overstay. Border officials werent letting us in without 72usd fine but we got it down to 40usd. The other border back to India that I know is from Sunauli( forgive the spelling) most likely to somewhere like Varanasi. Anyway Im getting off the point, happy border crossing