Lurker99, Twice in the last 5 years I haven't closed out my 401K and rolled it over to an IRA. I paid no taxes on my or my employer's share, but I'm quite sure that if you roll it over into a Roth IRA that taxes will be due on the whole amount.
"they are required by law to withhold 20% and to pay the govment'." This can be avoided by sending the rollover directly to the IRA. The brokerage firm, will usually supply you with the paperwork. I use one of the large firms and I do quite a bit of trading in this account. Because of the volume of trades I get what I think is a very fair rate. ($8 per trade)
Hope this helps but I agree with Diesel, check with an accountant or another expert in this field.