English term (edited): modern-ly

[This note is in support of Kiradenea’s answer. It may be graded but not selected.]
According to the Oxford English dictionary, ‘modernly’ has been around since 1605.
Here is the OED entry:
modernly adv.
1. In modern times. Now rare.
...
1856 Ulster Jrnl. Archæol. IV. 244 Bonaght was specially due on land modernly held by sorren tenure.
2. In a modern manner; after the fashion of modern times.
...
1868 Morn. Star 29 June, The Latin original reads to-day most modernly.
1887 Harper's Mag. July 315 Most modernly American as it is, it has a flavor one tastes in travels of old times.
3. Comb., as modernly-armed, written adjs.
1894 Westm. Gaz. 15 Oct. 5/1 The well-drilled and modernly-armed force which China can put in the field.
1905 Daily Chron. 28 Dec. 8/3 A modernly-written play.

Websters’s entry is:
1 : in modern times: now: society as modernly organized cannot tolerate so broad an area of official irresponsibility— R.H.Jackson
2 : in a modern manner: a modernly designed house; a modernly run office.

‘Modernly’ also appears in all the bigger single-volume dictionaries, though without examples.

On the Web, it is not to be found just on the sites of uneducated foreigners who play fast and loose with the language. If you run searches on “co.uk” sites as well as on “edu” and “ac.uk” sites, you will find many examples of its use.

Most of these examples are in the following combinations:
modernly equipped, modernly decorated, modernly furnished, modernly styled, modernly refurbished, modernly appointed, modernly designed
But also, e.g.:
modernly orchestrated
The sketches are modernly old-fashioned
Cumming is modernly camp and that is what made him famous, but this does not serve him well as a romantic lead. (from the Daily Telegraph)

In the Encyclopedia Britannica:
Perhaps the first country to develop a comprehensive and modernly efficient scheme of military education was Prussia...
First discovered modernly in 1938 by a woodcutter...
Anciently and modernly he has been a controversial person, but the very fury of the
controversy shows that he was a major figure of ancient history.

A9.com is Amazon’s search engine. One of the search options is to look for the word(s) in the titles or the content of books. You will find 398 uses of the word ‘modernly’ in books, 4 of them in titles.
E.g. one occurrence is in Buckminster Fuller’s “Critical Path”:
...Russians' "conventional" naval supremacy and its vastly greater numbers of modernly armed divisions...

In addition to the above documentation, I have to disagree with some of the other arguments:
“Not a common expression”: Even if we take Google’s findings with a pinch of salt, 9,000 occurrences of “modernly equipped” (let alone other combinations) make it quite a common expression, at least in the specific context.
“We cannot rely on Google as a linguistic authority”: No, but we can rely on our reading of the Google findings. And we do it all of the time.
“The English language does not need another invented word”: It is not an invented word. It has been around for five centuries. In any way, the English language is constantly enriched with new words, and that’s what makes it the richest language in the world.
In addition, in this case it is the best single word to express the meaning required. The only valid alternative, IMO, is David’s "equipped to the highest modern standards", six words for one.

I therefore think it is a perfectly acceptable word, well documented, used by many, and impossible to replace or improve on. As I said in my comment to Kiradenea’s answer, “I would use it in ‘modernly equipped’ even if I were the first one to do so”.

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Note added at 1 day 10 hrs 12 mins (2005-08-30 20:07:12 GMT) Post-grading
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Native speakers (or writers, if your prefer) who belong to the "pro-modernly" school of thought:
We were told in 1937 that there would be 1,750 first-line aircraft modernly equipped by April 1, 1938.
[The Second World War, Volume 1: The Gathering Storm by Winston S. Churchill]
We were lucky to get this place, which is furnished modernly and with good taste.
[Berlin Diary : The Journal of a Foreign Correspondent, 1934-1941 by William L. Shirer]
A bar, modernly decorated and obviously endowed with the best of intentions, but somehow strangely out of place in this respectable Swiss hostelry, ...
[Sketches from a Life by George F. Kennan]
Symbolism contains within itself a shift from a romantic to a modernly ironic aesthetic.
[Modernism : A Guide to European Literature 1890-1930 (Penguin Literary Criticism) by Malcolm Bradbury]
The family is wonderfully, modernly dysfunctional."
[Glenn Close, praising James Goldman’s Lion in Winter]
...untied her bonnet-strings and revealed herself as something at once agelessly primitive and most modernly degenerate.
[The Judge by Rebecca West]
Most of the writers of Frommer's Guides.