The American Heritage Dictionary of the English Language, 4th edition, which is reproduced at
http://www.bartleby.com/61/ contains an up-to-date list of Indo-European roots.
That same source has an article on "Indo-European and the Indo-Europeans" by Calvert Watkins at http://www.bartleby.com/61/8.html
To illustrate how close Latvian is lexically to proto-Indo-European, I just went through Watkins 7-page article and listed those hypothetical Indo-European roots (marked with an asterisk *) which are identical or nearly identical with Latvian. Most linguists do NOT know this kind of basic information about Latvian at all - they are incredibly ignorant and closed-minded in their own field, wallowing mostly in Greek and Latin and not paying attention to the evidence.
mainstream hypothetical
Indo-European Roots compared with still existing Latvian language
*do "give" = Latvian do (pronounced duo)
*ed "eat" = Latvian ed (Hittite ed-)
*ped "foot" = Latvian ped-
*es and *bheua- "expressing existence" = Latvian es ("I") esu ("am"),
bij-, bija "was"
*sen "old" = Latvian sen
*yeu- "youth" = Latvian jau-ns ("young")
*tu "you" = Latvian tu
*nes- "we" = Latvian mes
*yu- "you" = Latvian ju(s)
*persistent pronomial stems *to- and *ko = Latvian to and ko
*me- "measure" = Latvian me(r)
*sawel "Sun" = Latvian saule
*ster- "star" = Latvian stari "rays of light"
*aus- "East, to shine" = Latvian aus-trumi "East" aus-t "rise"
*nekt- "night" = Latvian nakt-
*sneigh "snow" = Latvian snieg
*deiw "divine bright sky, deus, God, Zeus" - Latvian diev-
*s(t)ena "thunder" = Latvian sitiena "strike, of a peal of thunder
*and lightning"
*dhghem- "earth" = Latvian zem- (dhgh = zh)
*ere "row" = Latvian aire
*ghwer "wild animal" = Latvain zver-
*vlko- "wolf" = Latvian vilku "of the wolf"
*wlp "fox" = Latvian lap-sa
*dhghu "fish" = Latvian zivu- "of the fish" (dhgh = zh)
*bhei "bee" = Latvian bi-te (also in ancient Egyptian bi-te)
*medhu "mead" = Latvian med- "honey"
*wi-ro "man" = Latvian vir-
*man "person" = Latvian man "mine, for me, for the self"
*mer- "to die" = Latvian mir-
*kerd- "heart" = Latvian sird-
*yek-r "liver" = Latvian ak-na
*s(w)e "self" = Lativan sev, sava
*mela "grinding" = Latvian mala
*egna "fire" = Latvian ugun, ugunis Latin ignis
*dhwer- "door" = Latvian dur- (Latvian caur, pronounced tsaur
= "through")
*nobh - "nobh" = Latvian naba
*kel-o "revolve, wheel" = Latvian cel-o "travel, road"
*wegh "vehicle transport" = Latvian vaga "rut"
*men- "mind" = Latvian min "mention", at-min "remember",
at-mina "memory"
reg- "tribal king" = Latvian rik-uo "lead, organize"
*legh- "law" = Latvian liek- "to set down", lik-ums "law,
lieg-t "forbid, prohibit", lik-t "bid, command"
Latin lex (Latvian legts "decided")
numbers (but these are pretty uniform in all Indo-European tongues)
*dwo = Latvian divi
*trei = Latvian tri(s)
*ketwer = Latvian chetri
*penke = Latvian pieci
*seks = Latvian sesh-
*septm = Latvian septin-
*okto(u) = Latvian asto-
*newn = Latvian dev-n-
*dekm = Latvian desm-
More on Indo-European roots will be forthcoming. Many hypothetical Indo-European roots are faulty, and we will be correcting them. Also some of the roots given above are not accurate and we will show where the errors have been made.