Privet!
Dear Jim,

I would like to tell you about my new job.

If you remember, in recent time('in recent time' можно, но по-моему как-то формально и не так уж много употребляется в разговорном языке. В большинстве случаев лучше нп. recently, lately, или, если речь идет о немножнко более продолжительном сроке, for some time now ) I have been working for ‘OldTelecom’ company in a ‘Fitter’ position as a fitter. There It was a hard job, but the main reason why I have decided to leave from ‘Oldtelecom’ is that my recent job was so boring! You cannot believe how tired I was after my work.

Meanwhile, Oldtelecom had given me very significant experience in telecommunications technologies and at the present time I am working for ‘NewTelecom’ company in ‘Expert’ position?? It is a great opportunity for my self-development and it is the most interesting job that I ['ve] ever had. Now I am responsible for the correct functioning of the most modern telecom equipment.

In addition, I should say that I have bought a new car. It is a sport coupe with a powerful engine. I would like to kindly invite you to make(BETTER: take, go out for) a test drive in my new car. I am sure you would like it.
Well, at this point I have to end my letter. I hope to hear from you soon.

All the best,
Oleg.